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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add(self, *args: Any, **kwargs: Any) -> Optional[Callable]: """ Register a function to the list. Args: *args: Set/Sequence of positional arguments. **kwargs: Mapping of named arguments. Raises: AttributeError: Raised if the method being added has no name. (i.e. it has no `__name__` property, and no `name` argument was given.) Examples: methods = Methods() @methods.add def subtract(minuend, subtrahend):
 return minuend - subtrahend """

        self.items = {
            **self.items,
            # Methods passed as positional args need a __name__ attribute, raises
            # AttributeError otherwise.
            **{m.__name__: validate(m) for m in args},
            **{k: validate(v) for k, v in kwargs.items()},
        }
        if len(args):
            return args[0]  # for the decorator to work
        return None