Update traits4.rs

Author: 13001288072

exercises/traits/traits4.rs

@@ -1,14 +1,3 @@
-// traits4.rs
-//
-// Your task is to replace the '??' sections so the code compiles.
-//
-// Don't change any line other than the marked one.
-//
-// Execute `rustlings hint traits4` or use the `hint` watch subcommand for a
-// hint.
-
-// I AM NOT DONE
-
 pub trait Licensed {
     fn licensing_info(&self) -> String {
         "some information".to_string()
@@ -23,7 +12,7 @@ impl Licensed for SomeSoftware {}
 impl Licensed for OtherSoftware {}
 
 // YOU MAY ONLY CHANGE THE NEXT LINE
-fn compare_license_types(software: ??, software_two: ??) -> bool {
+fn compare_license_types(software: &impl Licensed, software_two: &impl Licensed) -> bool {
     software.licensing_info() == software_two.licensing_info()
 }
 
@@ -36,14 +25,14 @@ mod tests {
         let some_software = SomeSoftware {};
         let other_software = OtherSoftware {};
 
-        assert!(compare_license_types(some_software, other_software));
+        assert!(compare_license_types(&some_software, &other_software));
     }
 
     #[test]
     fn compare_license_information_backwards() {
         let some_software = SomeSoftware {};
         let other_software = OtherSoftware {};
 
-        assert!(compare_license_types(other_software, some_software));
+        assert!(compare_license_types(&other_software, &some_software));
     }
 }