Return types

exam/classes/GUID/GUID.php

@@ -4,7 +4,7 @@ namespace Khofmann\GUID;
 
 class GUID
 {
-  public static function v4($data = null)
+  public static function v4($data = null): string
   {
     // Generate 16 bytes (128 bits) of random data or use the data passed into the function.
     $data = $data ?? random_bytes(16);