Simplified example with lifetimes specified

src/main.rs

@@ -6,7 +6,7 @@ fn main() {
     println!("The longest string is {result}");
 }
 
-fn longest(a: &str, b: &str) -> &str {
+fn longest<'a>(a: &'a str, b: &'a str) -> &'a str {
     if a.len() > b.len() {
         a
     } else {