code: def zadd(self, *args, **kwargs):
          
          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)
docs: 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.