diff --git a/exercises/clippy/clippy1.rs b/exercises/clippy/clippy1.rs
index bdb5dd2c..a5c5ce35 100644
--- a/exercises/clippy/clippy1.rs
+++ b/exercises/clippy/clippy1.rs
@@ -6,12 +6,12 @@
 // check clippy's suggestions from the output to solve the exercise.
 // Execute `rustlings hint clippy1` for hints :)
 
-// I AM NOT DONE
 
 fn main() {
     let x = 1.2331f64;
     let y = 1.2332f64;
-    if y != x {
+    let error_margin = 0.000001f64;
+    if (y - x).abs() > error_margin {
         println!("Success!");
     }
 }
diff --git a/exercises/clippy/clippy2.rs b/exercises/clippy/clippy2.rs
index 37af9ed0..4cdfbe75 100644
--- a/exercises/clippy/clippy2.rs
+++ b/exercises/clippy/clippy2.rs
@@ -1,12 +1,10 @@
 // clippy2.rs
 // Make me compile! Execute `rustlings hint clippy2` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let mut res = 42;
     let option = Some(12);
-    for x in option {
+    if let Some(x) = option {
         res += x;
     }
     println!("{}", res);
diff --git a/exercises/collections/hashmap1.rs b/exercises/collections/hashmap1.rs
index 64b5a7f3..cf65f94a 100644
--- a/exercises/collections/hashmap1.rs
+++ b/exercises/collections/hashmap1.rs
@@ -11,17 +11,16 @@
 // Execute the command `rustlings hint hashmap1` if you need
 // hints.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 fn fruit_basket() -> HashMap<String, u32> {
-    let mut basket = // TODO: declare your hash map here.
+    let mut basket = HashMap::new();
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
-
-    // TODO: Put more fruits in your basket here.
+    basket.insert(String::from("apples"), 5);
+    basket.insert(String::from("berries"), 7);
+    
 
     basket
 }
diff --git a/exercises/collections/hashmap2.rs b/exercises/collections/hashmap2.rs
index 0abe19ab..4339d333 100644
--- a/exercises/collections/hashmap2.rs
+++ b/exercises/collections/hashmap2.rs
@@ -11,9 +11,6 @@
 //
 // Execute the command `rustlings hint hashmap2` if you need
 // hints.
-
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(Hash, PartialEq, Eq)]
@@ -35,9 +32,7 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
     ];
 
     for fruit in fruit_kinds {
-        // TODO: Put new fruits if not already present. Note that you
-        // are not allowed to put any type of fruit that's already
-        // present!
+        basket.entry(fruit).or_insert(5);
     }
 }
 
diff --git a/exercises/collections/vec1.rs b/exercises/collections/vec1.rs
index b144fb94..6fb32a0f 100644
--- a/exercises/collections/vec1.rs
+++ b/exercises/collections/vec1.rs
@@ -4,11 +4,9 @@
 // Make me compile and pass the test!
 // Execute the command `rustlings hint vec1` if you need hints.
 
-// I AM NOT DONE
-
 fn array_and_vec() -> ([i32; 4], Vec<i32>) {
     let a = [10, 20, 30, 40]; // a plain array
-    let v = // TODO: declare your vector here with the macro for vectors
+    let v = vec![10,20,30,40];
 
     (a, v)
 }
diff --git a/exercises/collections/vec2.rs b/exercises/collections/vec2.rs
index 6595e401..2b85627b 100644
--- a/exercises/collections/vec2.rs
+++ b/exercises/collections/vec2.rs
@@ -7,12 +7,9 @@
 // Execute the command `rustlings hint vec2` if you need
 // hints.
 
-// I AM NOT DONE
-
 fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
     for i in v.iter_mut() {
-        // TODO: Fill this up so that each element in the Vec `v` is
-        // multiplied by 2.
+        *i *= 2;
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
diff --git a/exercises/conversions/as_ref_mut.rs b/exercises/conversions/as_ref_mut.rs
index 84f4a60c..32dcd78a 100644
--- a/exercises/conversions/as_ref_mut.rs
+++ b/exercises/conversions/as_ref_mut.rs
@@ -2,17 +2,18 @@
 // Read more about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html
 // and https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
 
-// I AM NOT DONE
-
 // Obtain the number of bytes (not characters) in the given argument
 // Add the AsRef trait appropriately as a trait bound
-fn byte_counter<T>(arg: T) -> usize {
+fn byte_counter<T>(arg: T) -> usize 
+where T: AsRef<str>  {
     arg.as_ref().as_bytes().len()
 }
 
 // Obtain the number of characters (not bytes) in the given argument
 // Add the AsRef trait appropriately as a trait bound
-fn char_counter<T>(arg: T) -> usize {
+fn char_counter<T>(arg: T) -> usize  
+where T: AsRef<str>
+{
     arg.as_ref().chars().count()
 }
 
diff --git a/exercises/conversions/from_into.rs b/exercises/conversions/from_into.rs
index 9d84174d..e2fbbb6f 100644
--- a/exercises/conversions/from_into.rs
+++ b/exercises/conversions/from_into.rs
@@ -33,10 +33,27 @@ impl Default for Person {
 // If while parsing the age, something goes wrong, then return the default of Person
 // Otherwise, then return an instantiated Person object with the results
 
-// I AM NOT DONE
 
 impl From<&str> for Person {
     fn from(s: &str) -> Person {
+        let mut idx = -1;
+        for (i, &b) in s.as_bytes().iter().enumerate() {
+            if b',' == b {
+                idx = i as i32;
+            }
+        }
+        if idx <= 0 || idx as usize == (s.len() - 1) {
+            Person::default()
+        }else {
+            let idx = idx as usize;
+            match s[(idx +1)..].parse::<usize>() {
+                Ok(age) => Person{
+                    name: s[..idx ].into(),
+                    age: age
+                },
+                Err(error) => Person::default()
+            }
+        }
     }
 }
 
diff --git a/exercises/conversions/from_str.rs b/exercises/conversions/from_str.rs
index 4beebacd..6b849c0d 100644
--- a/exercises/conversions/from_str.rs
+++ b/exercises/conversions/from_str.rs
@@ -4,6 +4,8 @@
 // You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html
 use std::error;
 use std::str::FromStr;
+use std::fmt::Display;
+use std::fmt::Formatter;
 
 #[derive(Debug)]
 struct Person {
@@ -11,8 +13,22 @@ struct Person {
     age: usize,
 }
 
-// I AM NOT DONE
+#[derive(Debug)]
+struct ParseError {
+    reason: String
+}
 
+impl Display for ParseError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), std::fmt::Error> 
+    { 
+        f.write_str("fucked up");
+        Ok(())
+    }
+}
+
+impl error::Error for ParseError {
+
+}
 // Steps:
 // 1. If the length of the provided string is 0, an error should be returned
 // 2. Split the given string on the commas present in it
@@ -26,6 +42,24 @@ struct Person {
 impl FromStr for Person {
     type Err = Box<dyn error::Error>;
     fn from_str(s: &str) -> Result<Person, Self::Err> {
+        let mut idx = -1;
+        for (i, &b) in s.as_bytes().iter().enumerate() {
+            if b',' == b {
+                idx = i as i32;
+            }
+        }
+        if idx <= 0 || idx as usize == (s.len() - 1) {
+            Err(Box::new(ParseError{reason:String::from("Not divided into two")}))
+        }else {
+            let idx = idx as usize;
+            match s[(idx +1)..].parse::<usize>() {
+                Ok(age) => Ok(Person{
+                    name: s[..idx ].into(),
+                    age: age
+                }),
+                Err(error) => Err(Box::new(ParseError{reason:String::from("invalid age string")}))
+            }
+        }
     }
 }
 
diff --git a/exercises/conversions/try_from_into.rs b/exercises/conversions/try_from_into.rs
index c0b5d986..bdbf7144 100644
--- a/exercises/conversions/try_from_into.rs
+++ b/exercises/conversions/try_from_into.rs
@@ -4,6 +4,7 @@
 // You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
 use std::convert::{TryFrom, TryInto};
 use std::error;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, PartialEq)]
 struct Color {
@@ -12,7 +13,35 @@ struct Color {
     blue: u8,
 }
 
-// I AM NOT DONE
+fn in_color_range(color_pt: i16) -> bool {
+    color_pt >=0 && color_pt <= 255
+}
+
+fn safe_to_i16(color_pt: i16) -> Option<u8> {
+    if in_color_range(color_pt) {
+        Some(color_pt as u8)
+    } else {
+        None
+    }
+}
+
+#[derive(Debug)]
+enum ConvertError{
+    BadInputs,
+    MoreBadInputs
+} 
+
+impl Display for ConvertError {
+    fn fmt(&self, a: &mut Formatter<'_>) -> Result<(), std::fmt::Error> 
+    { 
+        a.write_str("Bad");
+        Result::Ok(()) 
+    }
+}
+
+impl error::Error for ConvertError {
+
+}
 
 // Your task is to complete this implementation
 // and return an Ok result of inner type Color.
@@ -26,19 +55,51 @@ struct Color {
 // Tuple implementation
 impl TryFrom<(i16, i16, i16)> for Color {
     type Error = Box<dyn error::Error>;
-    fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {}
+    fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
+        if let (Some(r), Some(g), Some(b)) = (safe_to_i16(tuple.0),safe_to_i16(tuple.1), safe_to_i16(tuple.2)) {
+            Result::Ok(Color {
+                red: r,
+                green: g,
+                blue: b
+            })
+        } else {
+            Result::Err(Box::new(ConvertError::BadInputs))
+        }
+    }
 }
 
 // Array implementation
 impl TryFrom<[i16; 3]> for Color {
     type Error = Box<dyn error::Error>;
-    fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {}
+    fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
+        if let (Some(r), Some(g), Some(b)) = (safe_to_i16(arr[0]),safe_to_i16(arr[1]), safe_to_i16(arr[2])) {
+            Result::Ok(Color {
+                red: r,
+                green: g,
+                blue: b
+            })
+        } else {
+            Result::Err(Box::new(ConvertError::BadInputs))
+        }
+    }
 }
 
 // Slice implementation
 impl TryFrom<&[i16]> for Color {
     type Error = Box<dyn error::Error>;
-    fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {}
+    fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
+        if slice.len() != 3 {
+            Result::Err(Box::new(ConvertError::BadInputs))
+        } else if let (Some(r), Some(g), Some(b)) = (safe_to_i16(slice[0]),safe_to_i16(slice[1]), safe_to_i16(slice[2])) {
+            Result::Ok(Color {
+                red: r,
+                green: g,
+                blue: b
+            })
+        } else {
+            Result::Err(Box::new(ConvertError::BadInputs))
+        }
+    }
 }
 
 fn main() {
diff --git a/exercises/conversions/using_as.rs b/exercises/conversions/using_as.rs
index 821309ec..ff828080 100644
--- a/exercises/conversions/using_as.rs
+++ b/exercises/conversions/using_as.rs
@@ -5,11 +5,10 @@
 // The goal is to make sure that the division does not fail to compile
 // and returns the proper type.
 
-// I AM NOT DONE
 
 fn average(values: &[f64]) -> f64 {
     let total = values.iter().fold(0.0, |a, b| a + b);
-    total / values.len()
+    total / values.len() as f64
 }
 
 fn main() {
diff --git a/exercises/enums/enums1.rs b/exercises/enums/enums1.rs
index a2223d33..5f57a112 100644
--- a/exercises/enums/enums1.rs
+++ b/exercises/enums/enums1.rs
@@ -1,11 +1,12 @@
 // enums1.rs
 // Make me compile! Execute `rustlings hint enums1` for hints!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor
 }
 
 fn main() {
diff --git a/exercises/enums/enums2.rs b/exercises/enums/enums2.rs
index ec32d952..1c1d6ef7 100644
--- a/exercises/enums/enums2.rs
+++ b/exercises/enums/enums2.rs
@@ -1,11 +1,12 @@
 // enums2.rs
 // Make me compile! Execute `rustlings hint enums2` for hints!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 enum Message {
-    // TODO: define the different variants used below
+    Move{x:i32, y: i32},
+    Echo(String),
+    ChangeColor(i32, i32, i32),
+    Quit,
 }
 
 impl Message {
diff --git a/exercises/enums/enums3.rs b/exercises/enums/enums3.rs
index 178b40c4..10bbbc59 100644
--- a/exercises/enums/enums3.rs
+++ b/exercises/enums/enums3.rs
@@ -1,10 +1,11 @@
 // enums3.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
 enum Message {
-    // TODO: implement the message variant types based on their usage below
+    Move(Point),
+    Echo(String),
+    ChangeColor((u8, u8, u8)),
+    Quit,
 }
 
 struct Point {
@@ -36,7 +37,12 @@ impl State {
     }
 
     fn process(&mut self, message: Message) {
-        // TODO: create a match expression to process the different message variants
+        match message {
+            Message::Move(point) => {self.position = point},
+            Message::Echo(s) => {self.echo(s)},
+            Message::ChangeColor(i) => {self.color = i},
+            Message::Quit => self.quit = true
+        }
     }
 }
 
diff --git a/exercises/error_handling/errors1.rs b/exercises/error_handling/errors1.rs
index 9c24d85d..38b7c292 100644
--- a/exercises/error_handling/errors1.rs
+++ b/exercises/error_handling/errors1.rs
@@ -6,14 +6,12 @@
 // this function to have.
 // Execute `rustlings hint errors1` for hints!
 
-// I AM NOT DONE
-
-pub fn generate_nametag_text(name: String) -> Option<String> {
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
     if name.len() > 0 {
-        Some(format!("Hi! My name is {}", name))
+        Result::Ok((format!("Hi! My name is {}", name).to_string()))
     } else {
         // Empty names aren't allowed.
-        None
+        Result::Err("`name` was empty; it must be nonempty.".to_string())
     }
 }
 
@@ -28,7 +26,7 @@ mod tests {
     fn generates_nametag_text_for_a_nonempty_name() {
         assert_eq!(
             generate_nametag_text("Beyoncé".into()),
-            Some("Hi! My name is Beyoncé".into())
+            Result::Ok("Hi! My name is Beyoncé".into())
         );
     }
 
diff --git a/exercises/error_handling/errors2.rs b/exercises/error_handling/errors2.rs
index aad3a93f..478e3e45 100644
--- a/exercises/error_handling/errors2.rs
+++ b/exercises/error_handling/errors2.rs
@@ -16,14 +16,12 @@
 // There are at least two ways to implement this that are both correct-- but
 // one is a lot shorter! Execute `rustlings hint errors2` for hints to both ways.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
+    let qty = item_quantity.parse::<i32>()?;
 
     Ok(qty * cost_per_item + processing_fee)
 }
diff --git a/exercises/error_handling/errors3.rs b/exercises/error_handling/errors3.rs
index 460ac5c4..f928771e 100644
--- a/exercises/error_handling/errors3.rs
+++ b/exercises/error_handling/errors3.rs
@@ -4,22 +4,20 @@
 // Why not? What should we do to fix it?
 // Execute `rustlings hint errors3` for hints!
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
-fn main() {
+fn main() -> Result<(),ParseIntError>{
     let mut tokens = 100;
     let pretend_user_input = "8";
 
     let cost = total_cost(pretend_user_input)?;
 
-    if cost > tokens {
+    Ok(if cost > tokens {
         println!("You can't afford that many!");
     } else {
         tokens -= cost;
         println!("You now have {} tokens.", tokens);
-    }
+    })
 }
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
diff --git a/exercises/error_handling/errorsn.rs b/exercises/error_handling/errorsn.rs
index 5fe212bf..9dee2923 100644
--- a/exercises/error_handling/errorsn.rs
+++ b/exercises/error_handling/errorsn.rs
@@ -17,19 +17,17 @@
 //
 // Execute `rustlings hint errorsn` for hints :)
 
-// I AM NOT DONE
-
 use std::error;
 use std::fmt;
 use std::io;
 
 // PositiveNonzeroInteger is a struct defined below the tests.
-fn read_and_validate(b: &mut dyn io::BufRead) -> Result<PositiveNonzeroInteger, ???> {
+fn read_and_validate(b: &mut dyn io::BufRead) -> Result<PositiveNonzeroInteger, Box<dyn error::Error>> {
     let mut line = String::new();
-    b.read_line(&mut line);
-    let num: i64 = line.trim().parse();
-    let answer = PositiveNonzeroInteger::new(num);
-    answer
+    b.read_line(&mut line)?;
+    let num: i64 = line.trim().parse()?;
+    let answer = PositiveNonzeroInteger::new(num)?;
+    Ok(answer)
 }
 
 //
diff --git a/exercises/error_handling/result1.rs b/exercises/error_handling/result1.rs
index b978001b..7914441a 100644
--- a/exercises/error_handling/result1.rs
+++ b/exercises/error_handling/result1.rs
@@ -1,7 +1,6 @@
 // result1.rs
 // Make this test pass! Execute `rustlings hint result1` for hints :)
 
-// I AM NOT DONE
 
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
@@ -14,7 +13,13 @@ enum CreationError {
 
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
-        Ok(PositiveNonzeroInteger(value as u64))
+        if value < 0 {
+            return Result::Err(CreationError::Negative)
+        }else if value == 0 {
+            return Result::Err(CreationError::Zero)
+        }else {
+            Ok(PositiveNonzeroInteger(value as u64))
+        }
     }
 }
 
diff --git a/exercises/functions/functions1.rs b/exercises/functions/functions1.rs
index 31125278..c2dbfd4a 100644
--- a/exercises/functions/functions1.rs
+++ b/exercises/functions/functions1.rs
@@ -1,8 +1,10 @@
 // functions1.rs
 // Make me compile! Execute `rustlings hint functions1` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     call_me();
 }
+
+fn call_me() {
+    println!("Hi")
+}
diff --git a/exercises/functions/functions2.rs b/exercises/functions/functions2.rs
index 5721a172..03b2f654 100644
--- a/exercises/functions/functions2.rs
+++ b/exercises/functions/functions2.rs
@@ -1,13 +1,13 @@
 // functions2.rs
 // Make me compile! Execute `rustlings hint functions2` for hints :)
 
-// I AM NOT DONE
+
 
 fn main() {
     call_me(3);
 }
 
-fn call_me(num:) {
+fn call_me(num: i32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }
diff --git a/exercises/functions/functions3.rs b/exercises/functions/functions3.rs
index ed5f839f..cbcc04f0 100644
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -1,10 +1,9 @@
 // functions3.rs
 // Make me compile! Execute `rustlings hint functions3` for hints :)
 
-// I AM NOT DONE
 
 fn main() {
-    call_me();
+    call_me(45);
 }
 
 fn call_me(num: u32) {
diff --git a/exercises/functions/functions4.rs b/exercises/functions/functions4.rs
index 58637e4c..0c3c6c30 100644
--- a/exercises/functions/functions4.rs
+++ b/exercises/functions/functions4.rs
@@ -4,14 +4,13 @@
 // This store is having a sale where if the price is an even number, you get
 // 10 Rustbucks off, but if it's an odd number, it's 3 Rustbucks off.
 
-// I AM NOT DONE
 
 fn main() {
     let original_price = 51;
     println!("Your sale price is {}", sale_price(original_price));
 }
 
-fn sale_price(price: i32) -> {
+fn sale_price(price: i32) -> i32 {
     if is_even(price) {
         price - 10
     } else {
diff --git a/exercises/functions/functions5.rs b/exercises/functions/functions5.rs
index d22aa6c8..059e9295 100644
--- a/exercises/functions/functions5.rs
+++ b/exercises/functions/functions5.rs
@@ -1,13 +1,11 @@
 // functions5.rs
 // Make me compile! Execute `rustlings hint functions5` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let answer = square(3);
     println!("The answer is {}", answer);
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }
diff --git a/exercises/generics/generics1.rs b/exercises/generics/generics1.rs
index 967287ef..c255fced 100644
--- a/exercises/generics/generics1.rs
+++ b/exercises/generics/generics1.rs
@@ -1,9 +1,8 @@
 // This shopping list program isn't compiling!
 // Use your knowledge of generics to fix it.
 
-// I AM NOT DONE
 
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&str> = Vec::new();
     shopping_list.push("milk");
 }
diff --git a/exercises/generics/generics2.rs b/exercises/generics/generics2.rs
index 0cb59adc..57ae9486 100644
--- a/exercises/generics/generics2.rs
+++ b/exercises/generics/generics2.rs
@@ -1,14 +1,12 @@
 // This powerful wrapper provides the ability to store a positive integer value.
 // Rewrite it using generics so that it supports wrapping ANY type.
 
-// I AM NOT DONE
-
-struct Wrapper {
-    value: u32,
+struct Wrapper<T> {
+    value: T,
 }
 
-impl Wrapper {
-    pub fn new(value: u32) -> Self {
+impl<T> Wrapper<T> {
+    pub fn new(value: T) -> Self {
         Wrapper { value }
     }
 }
diff --git a/exercises/generics/generics3.rs b/exercises/generics/generics3.rs
index 64dd9bc1..bf850176 100644
--- a/exercises/generics/generics3.rs
+++ b/exercises/generics/generics3.rs
@@ -10,15 +10,14 @@
 
 // Execute 'rustlings hint generics3' for hints!
 
-// I AM NOT DONE
-
-pub struct ReportCard {
-    pub grade: f32,
+pub struct ReportCard<T:std::fmt::Display>
+{
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T:std::fmt::Display> ReportCard<T> {
     pub fn print(&self) -> String {
         format!("{} ({}) - achieved a grade of {}",
             &self.student_name, &self.student_age, &self.grade)
@@ -44,9 +43,8 @@ mod tests {
 
     #[test]
     fn generate_alphabetic_report_card() {
-        // TODO: Make sure to change the grade here after you finish the exercise.
         let report_card = ReportCard {
-            grade: 2.1,
+            grade: "A+",
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };
diff --git a/exercises/if/if1.rs b/exercises/if/if1.rs
index 90867545..8a2dde56 100644
--- a/exercises/if/if1.rs
+++ b/exercises/if/if1.rs
@@ -1,13 +1,12 @@
 // if1.rs
 
-// I AM NOT DONE
-
 pub fn bigger(a: i32, b: i32) -> i32 {
     // Complete this function to return the bigger number!
     // Do not use:
     // - another function call
     // - additional variables
     // Execute `rustlings hint if1` for hints
+    if a > b {a} else {b}
 }
 
 // Don't mind this for now :)
diff --git a/exercises/if/if2.rs b/exercises/if/if2.rs
index 80effbdf..545083a3 100644
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -4,13 +4,13 @@
 // Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
 // Execute the command `rustlings hint if2` if you want a hint :)
 
-// I AM NOT DONE
-
 pub fn fizz_if_foo(fizzish: &str) -> &str {
     if fizzish == "fizz" {
         "foo"
+    } else if fizzish == "fuzz" {
+        "bar"
     } else {
-        1
+        "baz"
     }
 }
 
diff --git a/exercises/macros/macros1.rs b/exercises/macros/macros1.rs
index ed0dac85..fee36ad2 100644
--- a/exercises/macros/macros1.rs
+++ b/exercises/macros/macros1.rs
@@ -1,8 +1,7 @@
 // macros1.rs
 // Make me compile! Execute `rustlings hint macros1` for hints :)
 
-// I AM NOT DONE
-
+#[macro_export]
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
@@ -10,5 +9,5 @@ macro_rules! my_macro {
 }
 
 fn main() {
-    my_macro();
+    my_macro!();
 }
diff --git a/exercises/macros/macros2.rs b/exercises/macros/macros2.rs
index d0be1236..6436dbde 100644
--- a/exercises/macros/macros2.rs
+++ b/exercises/macros/macros2.rs
@@ -1,12 +1,12 @@
 // macros2.rs
 // Make me compile! Execute `rustlings hint macros2` for hints :)
 
-// I AM NOT DONE
 
 fn main() {
     my_macro!();
 }
 
+#[macro_export]
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
diff --git a/exercises/macros/macros3.rs b/exercises/macros/macros3.rs
index 93a43113..fcd1fe91 100644
--- a/exercises/macros/macros3.rs
+++ b/exercises/macros/macros3.rs
@@ -2,14 +2,14 @@
 // Make me compile, without taking the macro out of the module!
 // Execute `rustlings hint macros3` for hints :)
 
-// I AM NOT DONE
-
 mod macros {
+    #[macro_export]
     macro_rules! my_macro {
         () => {
             println!("Check out my macro!");
         };
     }
+    pub(crate) use my_macro;
 }
 
 fn main() {
diff --git a/exercises/macros/macros4.rs b/exercises/macros/macros4.rs
index 3a748078..56930700 100644
--- a/exercises/macros/macros4.rs
+++ b/exercises/macros/macros4.rs
@@ -1,12 +1,10 @@
 // macros4.rs
 // Make me compile! Execute `rustlings hint macros4` for hints :)
 
-// I AM NOT DONE
-
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
-    }
+    };
     ($val:expr) => {
         println!("Look at this other macro: {}", $val);
     }
diff --git a/exercises/modules/modules1.rs b/exercises/modules/modules1.rs
index 812dfeef..c76b0586 100644
--- a/exercises/modules/modules1.rs
+++ b/exercises/modules/modules1.rs
@@ -1,10 +1,9 @@
 // modules1.rs
 // Make me compile! Execute `rustlings hint modules1` for hints :)
 
-// I AM NOT DONE
 
 mod sausage_factory {
-    fn make_sausage() {
+    pub fn make_sausage() {
         println!("sausage!");
     }
 }
diff --git a/exercises/modules/modules2.rs b/exercises/modules/modules2.rs
index fde439d1..50a3f080 100644
--- a/exercises/modules/modules2.rs
+++ b/exercises/modules/modules2.rs
@@ -1,11 +1,9 @@
 // modules2.rs
 // Make me compile! Execute `rustlings hint modules2` for hints :)
 
-// I AM NOT DONE
-
 mod delicious_snacks {
-    use self::fruits::PEAR as fruit;
-    use self::veggies::CUCUMBER as veggie;
+    pub use self::fruits::PEAR as fruit;
+    pub use self::veggies::CUCUMBER as veggie;
 
     mod fruits {
         pub const PEAR: &'static str = "Pear";
diff --git a/exercises/move_semantics/move_semantics1.rs b/exercises/move_semantics/move_semantics1.rs
index e2f5876d..a95f851a 100644
--- a/exercises/move_semantics/move_semantics1.rs
+++ b/exercises/move_semantics/move_semantics1.rs
@@ -1,12 +1,10 @@
 // move_semantics1.rs
 // Make me compile! Execute `rustlings hint move_semantics1` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let vec0 = Vec::new();
 
-    let vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(vec0);
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
diff --git a/exercises/move_semantics/move_semantics2.rs b/exercises/move_semantics/move_semantics2.rs
index bd21fbb7..f4330d36 100644
--- a/exercises/move_semantics/move_semantics2.rs
+++ b/exercises/move_semantics/move_semantics2.rs
@@ -2,27 +2,21 @@
 // Make me compile without changing line 13!
 // Execute `rustlings hint move_semantics2` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
-    let vec0 = Vec::new();
+    let mut vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    fill_vec(&mut vec0);
 
     // Do not change the following line!
     println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
 
-    vec1.push(88);
+    vec0.push(88);
 
-    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+    println!("{} has length {} content `{:?}`", "vec1", vec0.len(), vec0);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let mut vec = vec;
-
+fn fill_vec( vec:  &mut Vec<i32>) {
     vec.push(22);
     vec.push(44);
     vec.push(66);
-
-    vec
 }
diff --git a/exercises/move_semantics/move_semantics3.rs b/exercises/move_semantics/move_semantics3.rs
index 43fef74f..0fe1d858 100644
--- a/exercises/move_semantics/move_semantics3.rs
+++ b/exercises/move_semantics/move_semantics3.rs
@@ -3,10 +3,8 @@
 // (no lines with multiple semicolons necessary!)
 // Execute `rustlings hint move_semantics3` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
-    let vec0 = Vec::new();
+    let mut vec0 = Vec::new();
 
     let mut vec1 = fill_vec(vec0);
 
@@ -17,7 +15,7 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(mut vec:  Vec<i32>) -> Vec<i32> {
     vec.push(22);
     vec.push(44);
     vec.push(66);
diff --git a/exercises/move_semantics/move_semantics4.rs b/exercises/move_semantics/move_semantics4.rs
index 2a23c710..b8bf7cb9 100644
--- a/exercises/move_semantics/move_semantics4.rs
+++ b/exercises/move_semantics/move_semantics4.rs
@@ -4,12 +4,9 @@
 // freshly created vector from fill_vec to its caller.
 // Execute `rustlings hint move_semantics4` for hints!
 
-// I AM NOT DONE
-
 fn main() {
-    let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec();
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
@@ -20,7 +17,7 @@ fn main() {
 
 // `fill_vec()` no longer takes `vec: Vec<i32>` as argument
 fn fill_vec() -> Vec<i32> {
-    let mut vec = vec;
+    let mut vec = Vec::new();;
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/option/option1.rs b/exercises/option/option1.rs
index 602ff1a9..32d5aca0 100644
--- a/exercises/option/option1.rs
+++ b/exercises/option/option1.rs
@@ -1,23 +1,21 @@
 // option1.rs
 // Make me compile! Execute `rustlings hint option1` for hints
 
-// I AM NOT DONE
-
 // you can modify anything EXCEPT for this function's sig
 fn print_number(maybe_number: Option<u16>) {
     println!("printing: {}", maybe_number.unwrap());
 }
 
 fn main() {
-    print_number(13);
-    print_number(99);
+    print_number(Option::from(13));
+    print_number(Option::from(99));
 
-    let mut numbers: [Option<u16>; 5];
+    let mut numbers: [Option<u16>; 5] = [None; 5];
     for iter in 0..5 {
         let number_to_add: u16 = {
             ((iter * 1235) + 2) / (4 * 16)
         };
 
-        numbers[iter as usize] = number_to_add;
+        numbers[iter as usize] = Option::from(number_to_add);
     }
 }
diff --git a/exercises/option/option2.rs b/exercises/option/option2.rs
index c6b83ece..dba98730 100644
--- a/exercises/option/option2.rs
+++ b/exercises/option/option2.rs
@@ -1,12 +1,10 @@
 // option2.rs
 // Make me compile! Execute `rustlings hint option2` for hints
 
-// I AM NOT DONE
-
 fn main() {
     let optional_word = Some(String::from("rustlings"));
     // TODO: Make this an if let statement whose value is "Some" type
-    word = optional_word {
+    if let Some(word) = optional_word {
         println!("The word is: {}", word);
     } else {
         println!("The optional word doesn't contain anything");
@@ -19,7 +17,9 @@ fn main() {
 
     // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
     // You can stack `Option<T>`'s into while let and if let
-    integer = optional_integers_vec.pop() {
-        println!("current value: {}", integer);
+    while let Some(opt) = optional_integers_vec.pop() {
+        if let Some(integer) = opt {
+            println!("current value: {}", integer);
+        }
     }
 }
diff --git a/exercises/primitive_types/primitive_types1.rs b/exercises/primitive_types/primitive_types1.rs
index 09121392..715ca729 100644
--- a/exercises/primitive_types/primitive_types1.rs
+++ b/exercises/primitive_types/primitive_types1.rs
@@ -2,8 +2,6 @@
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
-// I AM NOT DONE
-
 fn main() {
     // Booleans (`bool`)
 
@@ -12,7 +10,7 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening = false;// Finish the rest of this line like the example! Or make it be false!
     if is_evening {
         println!("Good evening!");
     }
diff --git a/exercises/primitive_types/primitive_types2.rs b/exercises/primitive_types/primitive_types2.rs
index 6576a4d5..1703b9a7 100644
--- a/exercises/primitive_types/primitive_types2.rs
+++ b/exercises/primitive_types/primitive_types2.rs
@@ -2,7 +2,6 @@
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
-// I AM NOT DONE
 
 fn main() {
     // Characters (`char`)
@@ -16,9 +15,7 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
-    // Try a letter, try a number, try a special character, try a character
-    // from a different language than your own, try an emoji!
+    let your_character = '6';
     if your_character.is_alphabetic() {
         println!("Alphabetical!");
     } else if your_character.is_numeric() {
diff --git a/exercises/primitive_types/primitive_types3.rs b/exercises/primitive_types/primitive_types3.rs
index aaa518be..2d0af589 100644
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -2,10 +2,8 @@
 // Create an array with at least 100 elements in it where the ??? is.
 // Execute `rustlings hint primitive_types3` for hints!
 
-// I AM NOT DONE
-
 fn main() {
-    let a = ???
+    let a = [3,4,5,6,6,7,9];
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");
diff --git a/exercises/primitive_types/primitive_types4.rs b/exercises/primitive_types/primitive_types4.rs
index 10b553e9..d773c137 100644
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -2,13 +2,11 @@
 // Get a slice out of Array a where the ??? is so that the test passes.
 // Execute `rustlings hint primitive_types4` for hints!!
 
-// I AM NOT DONE
-
 #[test]
 fn slice_out_of_array() {
     let a = [1, 2, 3, 4, 5];
 
-    let nice_slice = ???
+    let nice_slice = &a[1..4];
 
     assert_eq!([2, 3, 4], nice_slice)
 }
diff --git a/exercises/primitive_types/primitive_types5.rs b/exercises/primitive_types/primitive_types5.rs
index 680d8d23..85f42cfc 100644
--- a/exercises/primitive_types/primitive_types5.rs
+++ b/exercises/primitive_types/primitive_types5.rs
@@ -2,11 +2,9 @@
 // Destructure the `cat` tuple so that the println will work.
 // Execute `rustlings hint primitive_types5` for hints!
 
-// I AM NOT DONE
-
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name, age) = cat;
 
     println!("{} is {} years old.", name, age);
 }
diff --git a/exercises/primitive_types/primitive_types6.rs b/exercises/primitive_types/primitive_types6.rs
index b8c9b82b..0c877aa6 100644
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -3,13 +3,11 @@
 // You can put the expression for the second element where ??? is so that the test passes.
 // Execute `rustlings hint primitive_types6` for hints!
 
-// I AM NOT DONE
-
 #[test]
 fn indexing_tuple() {
     let numbers = (1, 2, 3);
     // Replace below ??? with the tuple indexing syntax.
-    let second = ???;
+    let second = numbers.1;
 
     assert_eq!(2, second,
         "This is not the 2nd number in the tuple!")
diff --git a/exercises/quiz1.rs b/exercises/quiz1.rs
index 2bb2c24a..a31f4776 100644
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -7,10 +7,10 @@
 // more than 40 at once, each apple only costs 1! Write a function that calculates
 // the price of an order of apples given the order amount. No hints this time!
 
-// I AM NOT DONE
-
 // Put your function here!
-// fn ..... {
+ fn calculate_apple_price(count :i32)-> i32 {
+    count * if count > 40 {1} else {2}
+}
 
 // Don't modify this function!
 #[test]
diff --git a/exercises/quiz2.rs b/exercises/quiz2.rs
index de0dce95..613c1d92 100644
--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -7,8 +7,6 @@
 // you think each value is. That is, add either `string_slice` or `string`
 // before the parentheses on each line. If you're right, it will compile!
 
-// I AM NOT DONE
-
 fn string_slice(arg: &str) {
     println!("{}", arg);
 }
@@ -17,14 +15,14 @@ fn string(arg: String) {
 }
 
 fn main() {
-    ???("blue");
-    ???("red".to_string());
-    ???(String::from("hi"));
-    ???("rust is fun!".to_owned());
-    ???("nice weather".into());
-    ???(format!("Interpolation {}", "Station"));
-    ???(&String::from("abc")[0..1]);
-    ???("  hello there ".trim());
-    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+    string_slice("blue");
+    string("red".to_string());
+    string(String::from("hi"));
+    string("rust is fun!".to_owned());
+    string_slice("nice weather".into());
+    string(format!("Interpolation {}", "Station"));
+    string_slice(&String::from("abc")[0..1]);
+    string_slice("  hello there ".trim());
+    string("Happy Monday!".to_string().replace("Mon", "Tues"));
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
 }
diff --git a/exercises/quiz3.rs b/exercises/quiz3.rs
index fae0eedb..fb314e19 100644
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -7,8 +7,6 @@
 // we expect to get when we call `times_two` with a negative number.
 // No hints, you can do this :)
 
-// I AM NOT DONE
-
 pub fn times_two(num: i32) -> i32 {
     num * 2
 }
@@ -19,12 +17,12 @@ mod tests {
 
     #[test]
     fn returns_twice_of_positive_numbers() {
-        assert_eq!(times_two(4), ???);
+        assert_eq!(times_two(4), 8);
     }
 
     #[test]
     fn returns_twice_of_negative_numbers() {
         // TODO replace unimplemented!() with an assert for `times_two(-4)`
-        unimplemented!()
+        assert_eq!(times_two(-4),-8)
     }
 }
diff --git a/exercises/quiz4.rs b/exercises/quiz4.rs
index 6c47480d..b750b0ab 100644
--- a/exercises/quiz4.rs
+++ b/exercises/quiz4.rs
@@ -5,7 +5,12 @@
 
 // Write a macro that passes the quiz! No hints this time, you can do it!
 
-// I AM NOT DONE
+
+macro_rules! my_macro {
+    ($val: expr) => {
+        format!("{}{}","Hello ",  $val)
+    };
+}
 
 #[cfg(test)]
 mod tests {
diff --git a/exercises/standard_library_types/arc1.rs b/exercises/standard_library_types/arc1.rs
index d167380c..0965dd3d 100644
--- a/exercises/standard_library_types/arc1.rs
+++ b/exercises/standard_library_types/arc1.rs
@@ -18,19 +18,17 @@
 // where the second TODO comment is. Try not to create any copies of the `numbers` Vec!
 // Execute `rustlings hint arc1` for hints :)
 
-// I AM NOT DONE
-
 #![forbid(unused_imports)] // Do not change this, (or the next) line.
 use std::sync::Arc;
 use std::thread;
 
 fn main() {
     let numbers: Vec<_> = (0..100u32).collect();
-    let shared_numbers = // TODO
+    let shared_numbers = Arc::new(numbers);
     let mut joinhandles = Vec::new();
 
     for offset in 0..8 {
-        let child_numbers = // TODO
+        let child_numbers = Arc::clone(&shared_numbers);
         joinhandles.push(thread::spawn(move || {
             let mut i = offset;
             let mut sum = 0;
diff --git a/exercises/standard_library_types/box1.rs b/exercises/standard_library_types/box1.rs
index f312f3d6..6d18d9a3 100644
--- a/exercises/standard_library_types/box1.rs
+++ b/exercises/standard_library_types/box1.rs
@@ -16,11 +16,10 @@
 //
 // Execute `rustlings hint box1` for hints :)
 
-// I AM NOT DONE
 
 #[derive(PartialEq, Debug)]
 pub enum List {
-    Cons(i32, List),
+    Cons(i32, Box<List>),
     Nil,
 }
 
@@ -33,11 +32,11 @@ fn main() {
 }
 
 pub fn create_empty_list() -> List {
-    unimplemented!()
+    List::Nil
 }
 
 pub fn create_non_empty_list() -> List {
-    unimplemented!()
+    List::Cons(4, Box::new(List::Nil))
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators1.rs b/exercises/standard_library_types/iterators1.rs
index 3fd519d6..6da2012a 100644
--- a/exercises/standard_library_types/iterators1.rs
+++ b/exercises/standard_library_types/iterators1.rs
@@ -8,17 +8,16 @@
 // 
 // Execute `rustlings hint iterators1` for hints :D
 
-// I AM NOT DONE
 
 fn main () {
     let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
 
-    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1
+    let mut my_iterable_fav_fruits = my_fav_fruits.iter();   // TODO: Step 1
 
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"custard apple"));     // TODO: Step 2
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2.1
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach"));     // TODO: Step 2.1
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
+    assert_eq!(my_iterable_fav_fruits.next(), None);     // TODO: Step 3
 }
diff --git a/exercises/standard_library_types/iterators2.rs b/exercises/standard_library_types/iterators2.rs
index 87b4eaa1..5156829c 100644
--- a/exercises/standard_library_types/iterators2.rs
+++ b/exercises/standard_library_types/iterators2.rs
@@ -3,8 +3,6 @@
 // can offer. Follow the steps to complete the exercise.
 // As always, there are hints if you execute `rustlings hint iterators2`!
 
-// I AM NOT DONE
-
 // Step 1.
 // Complete the `capitalize_first` function.
 // "hello" -> "Hello"
@@ -12,7 +10,7 @@ pub fn capitalize_first(input: &str) -> String {
     let mut c = input.chars();
     match c.next() {
         None => String::new(),
-        Some(first) => ???,
+        Some(first) => first.to_uppercase().collect::<String>() + &c.collect::<String>(),
     }
 }
 
@@ -21,7 +19,7 @@ pub fn capitalize_first(input: &str) -> String {
 // Return a vector of strings.
 // ["hello", "world"] -> ["Hello", "World"]
 pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
-    vec![]
+    words.iter().map(|&v| capitalize_first(v)).collect()
 }
 
 // Step 3.
@@ -29,7 +27,7 @@ pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
 // Return a single string.
 // ["hello", " ", "world"] -> "Hello World"
 pub fn capitalize_words_string(words: &[&str]) -> String {
-    String::new()
+    capitalize_words_vector(words).join("")
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators3.rs b/exercises/standard_library_types/iterators3.rs
index 8c66c05b..4eb49ad0 100644
--- a/exercises/standard_library_types/iterators3.rs
+++ b/exercises/standard_library_types/iterators3.rs
@@ -6,8 +6,6 @@
 //    list_of_results functions.
 // Execute `rustlings hint iterators3` to get some hints!
 
-// I AM NOT DONE
-
 #[derive(Debug, PartialEq, Eq)]
 pub enum DivisionError {
     NotDivisible(NotDivisibleError),
@@ -22,20 +20,31 @@ pub struct NotDivisibleError {
 
 // Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
 // Otherwise, return a suitable error.
-pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {}
+pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
+    if b == 0 {
+        Result::Err(DivisionError::DivideByZero)
+    } else if a % b  > 0 {
+        Result::Err(DivisionError::NotDivisible(NotDivisibleError{dividend: a, divisor:b}))
+    }else {
+        Result::Ok(a / b)
+    }
+}
 
 // Complete the function and return a value of the correct type so the test passes.
 // Desired output: Ok([1, 11, 1426, 3])
-fn result_with_list() -> () {
+fn result_with_list() -> Result<Vec<i32>,DivisionError> {
     let numbers = vec![27, 297, 38502, 81];
     let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    Result::Ok(division_results
+        .filter_map(|n| n.ok()).collect())
 }
 
 // Complete the function and return a value of the correct type so the test passes.
 // Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
-fn list_of_results() -> () {
+fn list_of_results() -> Vec<Result<i32, DivisionError>> {
     let numbers = vec![27, 297, 38502, 81];
     let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    division_results.collect()
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators4.rs b/exercises/standard_library_types/iterators4.rs
index 88862838..7582c67a 100644
--- a/exercises/standard_library_types/iterators4.rs
+++ b/exercises/standard_library_types/iterators4.rs
@@ -1,17 +1,7 @@
 // iterators4.rs
 
-// I AM NOT DONE
-
 pub fn factorial(num: u64) -> u64 {
-    // Complete this function to return the factorial of num
-    // Do not use:
-    // - return
-    // Try not to use:
-    // - imperative style loops (for, while)
-    // - additional variables
-    // For an extra challenge, don't use:
-    // - recursion
-    // Execute `rustlings hint iterators4` for hints.
+    (1..=num).fold(1u64, |n, m| n *m)
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators5.rs b/exercises/standard_library_types/iterators5.rs
index d8d44537..58b1845e 100644
--- a/exercises/standard_library_types/iterators5.rs
+++ b/exercises/standard_library_types/iterators5.rs
@@ -11,8 +11,6 @@
 //
 // Make the code compile and the tests pass.
 
-// I AM NOT DONE
-
 use std::collections::HashMap;
 
 #[derive(PartialEq, Eq)]
@@ -33,8 +31,11 @@ fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
 }
 
 fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
-    // map is a hashmap with String keys and Progress values.
-    // map = { "variables1": Complete, "from_str": None, ... }
+    count_iterator_ref(map, &value)
+}
+
+fn count_iterator_ref(map: &HashMap<String, Progress>, value: &Progress) -> usize {
+    map.iter().map(|(_, progress)| { if progress == value {1} else {0}}).sum()
 }
 
 fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
@@ -50,9 +51,7 @@ fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progres
 }
 
 fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
-    // collection is a slice of hashmaps.
-    // collection = [{ "variables1": Complete, "from_str": None, ... },
-    //     { "variables2": Complete, ... }, ... ]
+    collection.iter().map(|collection| count_iterator_ref(collection, &value)).sum()
 }
 
 #[cfg(test)]
diff --git a/exercises/strings/strings1.rs b/exercises/strings/strings1.rs
index 80902444..21a0139b 100644
--- a/exercises/strings/strings1.rs
+++ b/exercises/strings/strings1.rs
@@ -2,13 +2,11 @@
 // Make me compile without changing the function signature!
 // Execute `rustlings hint strings1` for hints ;)
 
-// I AM NOT DONE
-
 fn main() {
     let answer = current_favorite_color();
     println!("My current favorite color is {}", answer);
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    "blue".to_string()
 }
diff --git a/exercises/strings/strings2.rs b/exercises/strings/strings2.rs
index 5a2ce74a..f910854a 100644
--- a/exercises/strings/strings2.rs
+++ b/exercises/strings/strings2.rs
@@ -2,11 +2,9 @@
 // Make me compile without changing the function signature!
 // Execute `rustlings hint strings2` for hints :)
 
-// I AM NOT DONE
-
 fn main() {
     let word = String::from("green"); // Try not changing this line :)
-    if is_a_color_word(word) {
+    if is_a_color_word(&word[..]) {
         println!("That is a color word I know!");
     } else {
         println!("That is not a color word I know.");
diff --git a/exercises/structs/structs1.rs b/exercises/structs/structs1.rs
index 6d0b2f49..92fb6efa 100644
--- a/exercises/structs/structs1.rs
+++ b/exercises/structs/structs1.rs
@@ -1,13 +1,12 @@
 // structs1.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
 struct ColorClassicStruct {
-    // TODO: Something goes here
+    name: String,
+    hex: String
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+struct ColorTupleStruct(String, String);
 
 #[derive(Debug)]
 struct UnitStruct;
@@ -19,7 +18,11 @@ mod tests {
     #[test]
     fn classic_c_structs() {
         // TODO: Instantiate a classic c struct!
-        // let green =
+        let green = ColorClassicStruct
+        {
+            name : "green".to_string(),
+            hex : "#00FF00".to_string()
+        };
 
         assert_eq!(green.name, "green");
         assert_eq!(green.hex, "#00FF00");
@@ -28,7 +31,7 @@ mod tests {
     #[test]
     fn tuple_structs() {
         // TODO: Instantiate a tuple struct!
-        // let green =
+        let green = ColorTupleStruct ("green".to_string(), "#00FF00".to_string());
 
         assert_eq!(green.0, "green");
         assert_eq!(green.1, "#00FF00");
@@ -37,7 +40,7 @@ mod tests {
     #[test]
     fn unit_structs() {
         // TODO: Instantiate a unit struct!
-        // let unit_struct =
+        let unit_struct = UnitStruct;
         let message = format!("{:?}s are fun!", unit_struct);
 
         assert_eq!(message, "UnitStructs are fun!");
diff --git a/exercises/structs/structs2.rs b/exercises/structs/structs2.rs
index f9c6427d..8ce1b4ad 100644
--- a/exercises/structs/structs2.rs
+++ b/exercises/structs/structs2.rs
@@ -1,8 +1,6 @@
 // structs2.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Order {
     name: String,
@@ -16,7 +14,7 @@ struct Order {
 
 fn create_order_template() -> Order {
     Order {
-        name: String::from("Bob"),
+        name: String::from("Hacker in Rust"),
         year: 2019,
         made_by_phone: false,
         made_by_mobile: false,
@@ -26,6 +24,18 @@ fn create_order_template() -> Order {
     }
 }
 
+fn create_my_order_template() -> Order {
+    Order {
+        name: String::from("Hacker in Rust"),
+        year: 2019,
+        made_by_phone: false,
+        made_by_mobile: false,
+        made_by_email: true,
+        item_number: 123,
+        count: 1
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -34,7 +44,7 @@ mod tests {
     fn your_order() {
         let order_template = create_order_template();
         // TODO: Create your own order using the update syntax and template above!
-        // let your_order =
+        let your_order = create_my_order_template();
         assert_eq!(your_order.name, "Hacker in Rust");
         assert_eq!(your_order.year, order_template.year);
         assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
diff --git a/exercises/structs/structs3.rs b/exercises/structs/structs3.rs
index 8d8b4710..e88d1627 100644
--- a/exercises/structs/structs3.rs
+++ b/exercises/structs/structs3.rs
@@ -4,8 +4,6 @@
 // Make the code compile and the tests pass!
 // If you have issues execute `rustlings hint structs3`
 
-// I AM NOT DONE
-
 #[derive(Debug)]
 struct Package {
     sender_country: String,
@@ -16,7 +14,7 @@ struct Package {
 impl Package {
     fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
         if weight_in_grams <= 0 {
-            // Something goes here...
+            panic!("Negative Weight!")
         } else {
             return Package {
                 sender_country,
@@ -26,12 +24,12 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
-        // Something goes here...
+    fn is_international(&self) -> bool {
+        self.sender_country != self.recipient_country
     }
 
-    fn get_fees(&self, cents_per_gram: i32) -> ??? {
-        // Something goes here... 
+    fn get_fees(&self, cents_per_gram: i32) -> i32 {
+        self.weight_in_grams * cents_per_gram
     }
 }
 
@@ -73,7 +71,7 @@ mod tests {
         let sender_country = String::from("Spain");
         let recipient_country = String::from("Spain");
 
-        let cents_per_gram = ???;
+        let cents_per_gram = 3;
 
         let package = Package::new(sender_country, recipient_country, 1500);
 
diff --git a/exercises/tests/tests1.rs b/exercises/tests/tests1.rs
index 50586a19..955f4232 100644
--- a/exercises/tests/tests1.rs
+++ b/exercises/tests/tests1.rs
@@ -6,12 +6,11 @@
 // This test has a problem with it -- make the test compile! Make the test
 // pass! Make the test fail! Execute `rustlings hint tests1` for hints :)
 
-// I AM NOT DONE
 
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert() {
-        assert!();
+        assert!(true);
     }
 }
diff --git a/exercises/tests/tests2.rs b/exercises/tests/tests2.rs
index 0d981ad1..1681aaa2 100644
--- a/exercises/tests/tests2.rs
+++ b/exercises/tests/tests2.rs
@@ -2,12 +2,11 @@
 // This test has a problem with it -- make the test compile! Make the test
 // pass! Make the test fail! Execute `rustlings hint tests2` for hints :)
 
-// I AM NOT DONE
 
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert_eq() {
-        assert_eq!();
+        assert_eq!(2,2);
     }
 }
diff --git a/exercises/tests/tests3.rs b/exercises/tests/tests3.rs
index 3424f940..36139a96 100644
--- a/exercises/tests/tests3.rs
+++ b/exercises/tests/tests3.rs
@@ -4,8 +4,6 @@
 // we expect to get when we call `is_even(5)`.
 // Execute `rustlings hint tests3` for hints :)
 
-// I AM NOT DONE
-
 pub fn is_even(num: i32) -> bool {
     num % 2 == 0
 }
@@ -16,11 +14,11 @@ mod tests {
 
     #[test]
     fn is_true_when_even() {
-        assert!();
+        assert!(is_even(4));
     }
 
     #[test]
     fn is_false_when_odd() {
-        assert!();
+        assert!(!is_even(7));
     }
 }
diff --git a/exercises/threads/threads1.rs b/exercises/threads/threads1.rs
index f31b317e..dc737b1d 100644
--- a/exercises/threads/threads1.rs
+++ b/exercises/threads/threads1.rs
@@ -6,26 +6,25 @@
 // of "waiting..." and the program ends without timing out when running,
 // you've got it :)
 
-// I AM NOT DONE
-
 use std::sync::Arc;
 use std::thread;
 use std::time::Duration;
+use std::sync::Mutex;
 
 struct JobStatus {
     jobs_completed: u32,
 }
 
 fn main() {
-    let status = Arc::new(JobStatus { jobs_completed: 0 });
+    let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));
     let status_shared = status.clone();
     thread::spawn(move || {
         for _ in 0..10 {
             thread::sleep(Duration::from_millis(250));
-            status_shared.jobs_completed += 1;
+            status_shared.lock().unwrap().jobs_completed += 1;
         }
     });
-    while status.jobs_completed < 10 {
+    while status.lock().unwrap().jobs_completed < 10 {
         println!("waiting... ");
         thread::sleep(Duration::from_millis(500));
     }
diff --git a/exercises/traits/traits1.rs b/exercises/traits/traits1.rs
index 2ef9e11b..69d56de7 100644
--- a/exercises/traits/traits1.rs
+++ b/exercises/traits/traits1.rs
@@ -8,14 +8,15 @@
 // which appends "Bar" to any object
 // implementing this trait.
 
-// I AM NOT DONE
 
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
 impl AppendBar for String {
-    //Add your code here
+    fn append_bar(self) -> Self {
+        self + "Bar"
+    }
 }
 
 fn main() {
diff --git a/exercises/traits/traits2.rs b/exercises/traits/traits2.rs
index 916c3c4b..5cd307da 100644
--- a/exercises/traits/traits2.rs
+++ b/exercises/traits/traits2.rs
@@ -10,13 +10,30 @@
 // No boiler plate code this time,
 // you can do this!
 
-// I AM NOT DONE
-
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
-//TODO: Add your code here
+
+impl AppendBar for &mut Vec<String> {
+    fn append_bar(self) -> Self {
+        self.push("Bar".to_owned());
+        println!("mut one");
+        return self
+    }
+}
+
+impl AppendBar for Vec<String> {
+    fn append_bar(self) -> Self {
+        let mut v : Vec<String> = vec![];
+        for s in self {
+            v.push(s.to_string());
+        }
+        println!("non mut one");
+        v.push("Bar".to_owned());
+        return v
+    }
+}
 
 #[cfg(test)]
 mod tests {
@@ -25,7 +42,12 @@ mod tests {
     #[test]
     fn is_vec_pop_eq_bar() {
         let mut foo = vec![String::from("Foo")].append_bar();
+        let mut a = vec![String::from("Foo")];
+        let mut a = (&mut a).append_bar();
+        
         assert_eq!(foo.pop().unwrap(), String::from("Bar"));
         assert_eq!(foo.pop().unwrap(), String::from("Foo"));
+        assert_eq!(a.pop().unwrap(), String::from("Bar"));
+        assert_eq!(a.pop().unwrap(), String::from("Foo"));
     }
 }
diff --git a/exercises/variables/variables1.rs b/exercises/variables/variables1.rs
index 4a3af73c..149d5ce8 100644
--- a/exercises/variables/variables1.rs
+++ b/exercises/variables/variables1.rs
@@ -6,9 +6,8 @@
 // even after you already figured it out. If you got everything working and
 // feel ready for the next exercise, remove the `I AM NOT DONE` comment below.
 
-// I AM NOT DONE
 
 fn main() {
-    x = 5;
+    let x = 5;
     println!("x has the value {}", x);
 }
diff --git a/exercises/variables/variables2.rs b/exercises/variables/variables2.rs
index 7774a8fb..b858f869 100644
--- a/exercises/variables/variables2.rs
+++ b/exercises/variables/variables2.rs
@@ -1,10 +1,9 @@
 // variables2.rs
 // Make me compile! Execute the command `rustlings hint variables2` if you want a hint :)
 
-// I AM NOT DONE
 
 fn main() {
-    let x;
+    let x = 55;
     if x == 10 {
         println!("Ten!");
     } else {
diff --git a/exercises/variables/variables3.rs b/exercises/variables/variables3.rs
index 30ec48ff..ddfa97f4 100644
--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -1,10 +1,11 @@
 // variables3.rs
 // Make me compile! Execute the command `rustlings hint variables3` if you want a hint :)
 
-// I AM NOT DONE
+
 
 fn main() {
-    let x = 3;
+    let mut x = 3;
+    
     println!("Number {}", x);
     x = 5; // don't change this line
     println!("Number {}", x);
diff --git a/exercises/variables/variables4.rs b/exercises/variables/variables4.rs
index 77f1e9ab..ba885231 100644
--- a/exercises/variables/variables4.rs
+++ b/exercises/variables/variables4.rs
@@ -1,9 +1,8 @@
 // variables4.rs
 // Make me compile! Execute the command `rustlings hint variables4` if you want a hint :)
 
-// I AM NOT DONE
 
 fn main() {
-    let x: i32;
+    let x: i32 = 4;
     println!("Number {}", x);
 }
diff --git a/exercises/variables/variables5.rs b/exercises/variables/variables5.rs
index da37ae99..10ef3140 100644
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -1,11 +1,9 @@
 // variables5.rs
 // Make me compile! Execute the command `rustlings hint variables5` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
     let number = "T-H-R-E-E";
     println!("Spell a Number : {}", number);
-    number = 3;
+    let number = 3;
     println!("Number plus two is : {}", number + 2);
 }
diff --git a/exercises/variables/variables6.rs b/exercises/variables/variables6.rs
index 98666914..ebd911d3 100644
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -1,9 +1,8 @@
 // variables6.rs
 // Make me compile! Execute the command `rustlings hint variables6` if you want a hint :)
 
-// I AM NOT DONE
 
-const NUMBER = 3;
+const NUMBER: i32 = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }