complete the exercises functions

exercises/02_functions/functions1.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint functions1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    call_me();
+    fn call_me() {};
 }

exercises/02_functions/functions2.rs

@@ -3,13 +3,11 @@
 // Execute `rustlings hint functions2` or use the `hint` watch subcommand for a
 // hint.
 
-// 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);
     }

exercises/02_functions/functions3.rs

@@ -3,10 +3,8 @@
 // Execute `rustlings hint functions3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
-    call_me();
+    call_me(3);
 }
 
 fn call_me(num: u32) {

exercises/02_functions/functions4.rs

@@ -8,14 +8,12 @@
 // Execute `rustlings hint functions4` or use the `hint` watch subcommand for a
 // hint.
 
-// 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 {

exercises/02_functions/functions5.rs

@@ -3,13 +3,11 @@
 // Execute `rustlings hint functions5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let answer = square(3);
     println!("The square of 3 is {}", answer);
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }