code: def sum_(expr):
      
  
      output_type = None
      if isinstance(expr, (SequenceExpr, SequenceGroupBy)):
          if expr._data_type == types.boolean:
              output_type = types.int64
          else:
              output_type = expr._data_type
      return _reduction(expr, Sum, output_type)
docs: Sum value
  
      :param expr:
      :return: