diff --git a/cache/solidity-files-cache.json b/cache/solidity-files-cache.json
new file mode 100644
index 00000000..bc6a474c
--- /dev/null
+++ b/cache/solidity-files-cache.json
@@ -0,0 +1,13 @@
+{
+  "_format": "ethers-rs-sol-cache-3",
+  "paths": {
+    "artifacts": "out",
+    "sources": "src",
+    "tests": "test",
+    "scripts": "script",
+    "libraries": [
+      "lib"
+    ]
+  },
+  "files": {}
+}
\ No newline at end of file
diff --git a/exercises/13_error_handling/errors1.rs b/exercises/13_error_handling/errors1.rs
index 0ba59a57..b52d940a 100644
--- a/exercises/13_error_handling/errors1.rs
+++ b/exercises/13_error_handling/errors1.rs
@@ -9,14 +9,14 @@
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
 // hint.
 
-// 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.is_empty() {
         // Empty names aren't allowed.
-        None
+        Err("`name` was empty; it must be nonempty.".to_string())
     } else {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     }
 }
 
diff --git a/exercises/13_error_handling/errors2.rs b/exercises/13_error_handling/errors2.rs
index 631fe67f..baaa0f8c 100644
--- a/exercises/13_error_handling/errors2.rs
+++ b/exercises/13_error_handling/errors2.rs
@@ -19,14 +19,13 @@
 // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a
 // hint.
 
-// 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/13_error_handling/errors3.rs b/exercises/13_error_handling/errors3.rs
index d42d3b17..634a7e16 100644
--- a/exercises/13_error_handling/errors3.rs
+++ b/exercises/13_error_handling/errors3.rs
@@ -7,7 +7,6 @@
 // Execute `rustlings hint errors3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 use std::num::ParseIntError;
 
@@ -15,7 +14,7 @@ fn main() {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
-    let cost = total_cost(pretend_user_input)?;
+    let cost = total_cost(pretend_user_input).unwrap();
 
     if cost > tokens {
         println!("You can't afford that many!");
diff --git a/exercises/13_error_handling/errors4.rs b/exercises/13_error_handling/errors4.rs
index d6d6fcb6..fe804944 100644
--- a/exercises/13_error_handling/errors4.rs
+++ b/exercises/13_error_handling/errors4.rs
@@ -3,7 +3,6 @@
 // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
@@ -17,7 +16,18 @@ enum CreationError {
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
         // Hmm... Why is this always returning an Ok value?
-        Ok(PositiveNonzeroInteger(value as u64))
+        if value > 0
+        {
+            Ok(PositiveNonzeroInteger(value as u64))
+        }
+        else if value == 0
+        {
+            Err(CreationError::Zero)
+        }
+        else
+        {
+            Err(CreationError::Negative)
+        }
     }
 }
 
diff --git a/exercises/13_error_handling/errors5.rs b/exercises/13_error_handling/errors5.rs
index 92461a7e..1e5d8bde 100644
--- a/exercises/13_error_handling/errors5.rs
+++ b/exercises/13_error_handling/errors5.rs
@@ -22,14 +22,13 @@
 // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 use std::error;
 use std::fmt;
 use std::num::ParseIntError;
 
 // TODO: update the return type of `main()` to make this compile.
-fn main() -> Result<(), Box<dyn ???>> {
+fn main() -> Result<(), Box<dyn error::Error >> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);
diff --git a/exercises/13_error_handling/errors6.rs b/exercises/13_error_handling/errors6.rs
index aaf0948e..9ef7aa6a 100644
--- a/exercises/13_error_handling/errors6.rs
+++ b/exercises/13_error_handling/errors6.rs
@@ -9,7 +9,6 @@
 // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 use std::num::ParseIntError;
 
@@ -25,13 +24,16 @@ impl ParsePosNonzeroError {
         ParsePosNonzeroError::Creation(err)
     }
     // TODO: add another error conversion function here.
-    // fn from_parseint...
+    fn from_parseint(err: ParseIntError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::ParseInt(err)
+    }
 }
 
 fn parse_pos_nonzero(s: &str) -> Result<PositiveNonzeroInteger, ParsePosNonzeroError> {
     // TODO: change this to return an appropriate error instead of panicking
     // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
+    let x : i64 =  s.parse().map_err(ParsePosNonzeroError::from_parseint)?;
+  
     PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
 }
 
diff --git a/exercises/14_generics/generics1.rs b/exercises/14_generics/generics1.rs
index 35c1d2fe..037e3c77 100644
--- a/exercises/14_generics/generics1.rs
+++ b/exercises/14_generics/generics1.rs
@@ -6,9 +6,8 @@
 // Execute `rustlings hint generics1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&'static str> = Vec::new();
     shopping_list.push("milk");
 }
diff --git a/exercises/14_generics/generics2.rs b/exercises/14_generics/generics2.rs
index 074cd938..f9493558 100644
--- a/exercises/14_generics/generics2.rs
+++ b/exercises/14_generics/generics2.rs
@@ -6,14 +6,13 @@
 // Execute `rustlings hint generics2` or use the `hint` watch subcommand for a
 // hint.
 
-// 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/15_traits/traits1.rs b/exercises/15_traits/traits1.rs
index 37dfcbfe..bb36133e 100644
--- a/exercises/15_traits/traits1.rs
+++ b/exercises/15_traits/traits1.rs
@@ -7,7 +7,7 @@
 // Execute `rustlings hint traits1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+
 
 trait AppendBar {
     fn append_bar(self) -> Self;
@@ -15,6 +15,9 @@ trait AppendBar {
 
 impl AppendBar for String {
     // TODO: Implement `AppendBar` for type `String`.
+    fn append_bar(self) -> Self {
+        self + "Bar"
+    }
 }
 
 fn main() {
diff --git a/exercises/15_traits/traits2.rs b/exercises/15_traits/traits2.rs
index 3e35f8e1..b96e0b9d 100644
--- a/exercises/15_traits/traits2.rs
+++ b/exercises/15_traits/traits2.rs
@@ -8,13 +8,19 @@
 //
 // Execute `rustlings hint traits2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
 
 trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
 // TODO: Implement trait `AppendBar` for a vector of strings.
+impl AppendBar for Vec<String> {
+    fn append_bar(mut self) -> Self {
+        
+        self.push(String::from("Bar"));
+        self
+    }
+}
 
 #[cfg(test)]
 mod tests {
diff --git a/exercises/15_traits/traits3.rs b/exercises/15_traits/traits3.rs
index 4e2b06b0..ee1ebfb2 100644
--- a/exercises/15_traits/traits3.rs
+++ b/exercises/15_traits/traits3.rs
@@ -8,10 +8,12 @@
 // Execute `rustlings hint traits3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 pub trait Licensed {
-    fn licensing_info(&self) -> String;
+    fn licensing_info(&self) -> String
+    {
+        String::from("Some information")
+    }
 }
 
 struct SomeSoftware {
@@ -22,7 +24,7 @@ struct OtherSoftware {
     version_number: String,
 }
 
-impl Licensed for SomeSoftware {} // Don't edit this line
+impl Licensed for SomeSoftware {}// Don't edit this line
 impl Licensed for OtherSoftware {} // Don't edit this line
 
 #[cfg(test)]
diff --git a/exercises/15_traits/traits4.rs b/exercises/15_traits/traits4.rs
index 4bda3e57..690395bf 100644
--- a/exercises/15_traits/traits4.rs
+++ b/exercises/15_traits/traits4.rs
@@ -7,7 +7,6 @@
 // Execute `rustlings hint traits4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 pub trait Licensed {
     fn licensing_info(&self) -> String {
@@ -23,7 +22,7 @@ impl Licensed for SomeSoftware {}
 impl Licensed for OtherSoftware {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn compare_license_types(software: ??, software_two: ??) -> bool {
+fn compare_license_types(software: impl Licensed, software_two: impl Licensed) -> bool {
     software.licensing_info() == software_two.licensing_info()
 }
 
diff --git a/exercises/15_traits/traits5.rs b/exercises/15_traits/traits5.rs
index df183805..189e93ae 100644
--- a/exercises/15_traits/traits5.rs
+++ b/exercises/15_traits/traits5.rs
@@ -7,7 +7,6 @@
 // Execute `rustlings hint traits5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 pub trait SomeTrait {
     fn some_function(&self) -> bool {
@@ -30,7 +29,7 @@ impl SomeTrait for OtherStruct {}
 impl OtherTrait for OtherStruct {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn some_func(item: ??) -> bool {
+fn some_func(item: impl SomeTrait + OtherTrait) -> bool {
     item.some_function() && item.other_function()
 }
 
diff --git a/exercises/16_lifetimes/lifetimes1.rs b/exercises/16_lifetimes/lifetimes1.rs
index 87bde490..357fa8e9 100644
--- a/exercises/16_lifetimes/lifetimes1.rs
+++ b/exercises/16_lifetimes/lifetimes1.rs
@@ -8,9 +8,8 @@
 // Execute `rustlings hint lifetimes1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
-fn longest(x: &str, y: &str) -> &str {
+fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
     if x.len() > y.len() {
         x
     } else {
diff --git a/exercises/16_lifetimes/lifetimes2.rs b/exercises/16_lifetimes/lifetimes2.rs
index 4f3d8c18..f26ab3fa 100644
--- a/exercises/16_lifetimes/lifetimes2.rs
+++ b/exercises/16_lifetimes/lifetimes2.rs
@@ -6,7 +6,6 @@
 // Execute `rustlings hint lifetimes2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
     if x.len() > y.len() {
@@ -22,6 +21,7 @@ fn main() {
     {
         let string2 = String::from("xyz");
         result = longest(string1.as_str(), string2.as_str());
+        println!("The longest string is '{}'", result);
     }
-    println!("The longest string is '{}'", result);
+    
 }
diff --git a/exercises/16_lifetimes/lifetimes3.rs b/exercises/16_lifetimes/lifetimes3.rs
index 9c59f9c0..2507d59b 100644
--- a/exercises/16_lifetimes/lifetimes3.rs
+++ b/exercises/16_lifetimes/lifetimes3.rs
@@ -5,11 +5,10 @@
 // Execute `rustlings hint lifetimes3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
-struct Book {
-    author: &str,
-    title: &str,
+struct Book<'a> {
+    author: &'a str,
+    title: &'a str,
 }
 
 fn main() {
diff --git a/exercises/17_tests/tests1.rs b/exercises/17_tests/tests1.rs
index 810277ac..a4808c5f 100644
--- a/exercises/17_tests/tests1.rs
+++ b/exercises/17_tests/tests1.rs
@@ -10,12 +10,11 @@
 // Execute `rustlings hint tests1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert() {
-        assert!();
+        assert!(true);
     }
 }
diff --git a/exercises/17_tests/tests2.rs b/exercises/17_tests/tests2.rs
index f8024e9f..d93ea05d 100644
--- a/exercises/17_tests/tests2.rs
+++ b/exercises/17_tests/tests2.rs
@@ -6,12 +6,11 @@
 // Execute `rustlings hint tests2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 #[cfg(test)]
 mod tests {
     #[test]
     fn you_can_assert_eq() {
-        assert_eq!();
+        assert_eq!(1,1);
     }
 }
diff --git a/exercises/17_tests/tests3.rs b/exercises/17_tests/tests3.rs
index 4013e384..073fb32a 100644
--- a/exercises/17_tests/tests3.rs
+++ b/exercises/17_tests/tests3.rs
@@ -7,8 +7,6 @@
 // Execute `rustlings hint tests3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 pub fn is_even(num: i32) -> bool {
     num % 2 == 0
 }
@@ -19,11 +17,11 @@ mod tests {
 
     #[test]
     fn is_true_when_even() {
-        assert!();
+        assert!(is_even(2));
     }
 
     #[test]
     fn is_false_when_odd() {
-        assert!();
+        assert!(!is_even(5));
     }
 }
diff --git a/exercises/17_tests/tests4.rs b/exercises/17_tests/tests4.rs
index 935d0db1..df624157 100644
--- a/exercises/17_tests/tests4.rs
+++ b/exercises/17_tests/tests4.rs
@@ -5,7 +5,6 @@
 // Execute `rustlings hint tests4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 struct Rectangle {
     width: i32,
@@ -30,17 +29,20 @@ mod tests {
     fn correct_width_and_height() {
         // This test should check if the rectangle is the size that we pass into its constructor
         let rect = Rectangle::new(10, 20);
-        assert_eq!(???, 10); // check width
-        assert_eq!(???, 20); // check height
+        assert_eq!(rect.width, 10); // check width
+        assert_eq!(rect.height, 20); // check height
     }
 
     #[test]
+    #[should_panic]
     fn negative_width() {
         // This test should check if program panics when we try to create rectangle with negative width
         let _rect = Rectangle::new(-10, 10);
     }
 
     #[test]
+    #[should_panic]
+
     fn negative_height() {
         // This test should check if program panics when we try to create rectangle with negative height
         let _rect = Rectangle::new(10, -10);
diff --git a/exercises/18_iterators/iterators1.rs b/exercises/18_iterators/iterators1.rs
index 31076bb9..721b2efa 100644
--- a/exercises/18_iterators/iterators1.rs
+++ b/exercises/18_iterators/iterators1.rs
@@ -9,18 +9,18 @@
 // Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+
 
 #[test]
 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 3
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach"));     // TODO: Step 3
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 4
+    assert_eq!(my_iterable_fav_fruits.next(), None);     // TODO: Step 4
 }
diff --git a/exercises/18_iterators/iterators2.rs b/exercises/18_iterators/iterators2.rs
index dda82a08..409b887b 100644
--- a/exercises/18_iterators/iterators2.rs
+++ b/exercises/18_iterators/iterators2.rs
@@ -6,7 +6,6 @@
 // Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 // Step 1.
 // Complete the `capitalize_first` function.
@@ -15,7 +14,7 @@ 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().to_string() + c.as_str()
     }
 }
 
@@ -24,7 +23,13 @@ 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(|input| capitalize_first(*input)).collect()
+    // let mut x : Vec<String> = vec![];
+    // for word in words.iter()
+    // {
+    //     x.push(capitalize_first(word));
+    // }
+    // x
 }
 
 // Step 3.
@@ -32,7 +37,18 @@ 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()
+    words.iter().map(|input| capitalize_first(*input)).collect()
+    // for word in words.iter()
+    // {
+    //     if word == &" "
+    //     {
+    //         x.push_str(word);
+    //     } else {
+    //         x.push_str(&capitalize_first(word))
+    //     }
+        
+    // }
+    //x
 }
 
 #[cfg(test)]
diff --git a/exercises/18_iterators/iterators3.rs b/exercises/18_iterators/iterators3.rs
index 29fa23a3..9e3b090d 100644
--- a/exercises/18_iterators/iterators3.rs
+++ b/exercises/18_iterators/iterators3.rs
@@ -9,7 +9,6 @@
 // Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 #[derive(Debug, PartialEq, Eq)]
 pub enum DivisionError {
@@ -26,23 +25,32 @@ 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> {
-    todo!();
+    if b == 0 {
+        Err(DivisionError::DivideByZero)
+    } else if a%b == 0 {
+        Ok(a / b)
+    } else {
+        Err(DivisionError::NotDivisible(NotDivisibleError{dividend: a, divisor: 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));
+    let division_results = numbers.into_iter().map(|n| divide(n,27));
+    division_results.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.filter(|x| x.is_ok()).collect()
 }
 
 #[cfg(test)]
diff --git a/exercises/18_iterators/iterators4.rs b/exercises/18_iterators/iterators4.rs
index 79e1692b..53827461 100644
--- a/exercises/18_iterators/iterators4.rs
+++ b/exercises/18_iterators/iterators4.rs
@@ -3,9 +3,9 @@
 // Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 pub fn factorial(num: u64) -> u64 {
+    (1..num+1).into_iter().fold(1, |acc, x| x * acc)
     // Complete this function to return the factorial of num
     // Do not use:
     // - return
diff --git a/exercises/quiz3.rs b/exercises/quiz3.rs
index 3b01d313..f3900dab 100644
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -16,15 +16,17 @@
 //
 // Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
 
-pub struct ReportCard {
-    pub grade: f32,
+
+use std::fmt::Display;
+
+pub struct ReportCard<T : Display> {
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T : Display> ReportCard<T> {
     pub fn print(&self) -> String {
         format!("{} ({}) - achieved a grade of {}",
             &self.student_name, &self.student_age, &self.grade)
@@ -52,7 +54,7 @@ mod tests {
     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,
         };