code: def cumsum(expr, sort=None, ascending=True, unique=False,
             preceding=None, following=None):
      if expr._data_type == types.boolean:
          output_type = types.int64
      else:
          output_type = expr._data_type
      return _cumulative_op(expr, CumSum, sort=sort, ascending=ascending,
                            unique=unique, preceding=preceding,
                            following=following, data_type=output_type)