code: def groupby(expr, by, *bys):
      
  
      if not isinstance(by, list):
          by = [by, ]
      if len(bys) > 0:
          by = by + list(bys)
      return GroupBy(_input=expr, _by=by)
docs: Group collection by a series of sequences.
  
      :param expr: collection
      :param by: columns to group
      :param bys: columns to group
      :return: GroupBy instance
      :rtype: :class:`odps.df.expr.groupby.GroupBy`