input: Write a python function to create a decorator that prints a message before and after the execution of a function.
  assert my_decorator(lambda: print("Test"))() == None
  assert my_decorator(lambda: print("Another Test"))() == None
output: def my_decorator(func):
      def wrapper():
          print("Before the function execution.")
          result = func()
          print("After the function execution.")
          return result
      return wrapper