Complete functions section

exercises/functions/functions1.rs

@@ -1,6 +1,10 @@
 // functions1.rs
 // Make me compile! Scroll down for hints :)
 
+fn call_me() -> () {
+    println!("I have been called!");
+}
+
 fn main() {
     call_me();
 }

exercises/functions/functions2.rs

@@ -5,7 +5,7 @@ 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/functions/functions3.rs

@@ -2,7 +2,7 @@
 // Make me compile! Scroll down for hints :)
 
 fn main() {
-    call_me();
+    call_me(12);
 }
 
 fn call_me(num: i32) {

exercises/functions/functions4.rs

@@ -9,7 +9,7 @@ fn main() {
     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/functions/functions5.rs

@@ -7,7 +7,7 @@ fn main() {
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }