Parse args and kwargs to check values to pass them through the
        from_python method.
        We pass the parsed args/kwargs as args in the super call, to avoid
        doing the same calculation on kwargs one more time.

def zadd(self, *args, **kwargs):
        """
        Parse args and kwargs to check values to pass them through the
        from_python method.
        We pass the parsed args/kwargs as args in the super call, to avoid
        doing the same calculation on kwargs one more time.
        """
        if 'values_callback' not in kwargs:
            kwargs['values_callback'] = self.from_python_many
        pieces = fields.SortedSetField.coerce_zadd_args(*args, **kwargs)
        return super(M2MSortedSetField, self).zadd(*pieces)