Method Wrappers can add hidden behavior to a method without recompiling it. They can be used to change a method's behavior. Commonly, they are used to add behavior before and after the default method executes. For example, we can create a coverage tool by using a method wrapper that increments a counter when it is called. If you would like more detailed information about method wrappers, you can read the ECOOP'98 paper Wrappers to the Rescue.