code: def moment(expr, order, central=False):
      
      if not isinstance(order, six.integer_types):
          raise ValueError('Only integer-ordered moments are supported.')
      if order < 0:
          raise ValueError('Only non-negative orders are supported.')
      output_type = _stats_type(expr)
      return _reduction(expr, Moment, output_type, _order=order, _center=central)
docs: Calculate the n-th order moment of the sequence
  
      :param expr:
      :param order: moment order, must be an integer
      :param central: if central moments are to be computed.
      :return: