code: def copy_docstring(source_class):
      
      def decorator(method):
          """Decorator implementation.
  
          Args:
              method (Callable): The method to copy the docstring to.
  
          Returns:
              Callable: the same method passed in with an updated docstring.
  
          Raises:
              ValueError: if the method already has a docstring.
          """
          if method.__doc__:
              raise ValueError('Method already has a docstring.')
  
          source_method = getattr(source_class, method.__name__)
          method.__doc__ = source_method.__doc__
  
          return method
      return decorator
docs: Decorator that copies a method's docstring from another class.
  
      Args:
          source_class (type): The class that has the documented method.
  
      Returns:
          Callable: A decorator that will copy the docstring of the same
              named method in the source class to the decorated method.