right let's try this one again

exercises/functions/functions5.rs

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+// functions5.rs
+// Make me compile! Scroll down for hints :)
+
+fn main() {
+    let answer = square(3);
+    println!("The answer is {}", answer);
+}
+
+fn square(num: i32) -> i32 {
+    num * num;
+}
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+// This is a really common error that can be fixed by removing one character.
+// It happens because Rust distinguishes between expressions and statements: expressions return
+// a value based on its operand, and statements simply return a () type which behaves just like `void` in C/C++ language. 
+// We want to return a value of `i32` type from the `square` function, but it is returning a `()` type...
+// They are not the same. There are two solutions:
+// 1. Add a `return` ahead of `num * num;`
+// 2. remove `;`, make it to be `num * num`