rustlings vec primitive types

exercises/02_functions/functions5.rs

@@ -0,0 +1,9 @@
+// TODO: Fix the function body without changing the signature.
+fn square(num: i32) -> i32 {
+    num * num
+}
+
+fn main() {
+    let answer = square(3);
+    println!("The square of 3 is {}", answer);
+}