code: def groupby(
              self,
              by=None,
              axis=0,
              level=None,
              as_index=True,
              sort=False,
              group_keys=False,
              squeeze=False,
              **kwargs
      ):
          
  
          if by == self.index.names[1]:
              by = None
              level = 1
          elif by == self.index.names[0]:
              by = None
              level = 0
          return self.data.groupby(
              by=by,
              axis=axis,
              level=level,
              as_index=as_index,
              sort=sort,
              group_keys=group_keys,
              squeeze=squeeze
          )
docs: 仿dataframe的groupby写法,但控制了by的code和datetime
  
          Keyword Arguments:
              by {[type]} -- [description] (default: {None})
              axis {int} -- [description] (default: {0})
              level {[type]} -- [description] (default: {None})
              as_index {bool} -- [description] (default: {True})
              sort {bool} -- [description] (default: {True})
              group_keys {bool} -- [description] (default: {True})
              squeeze {bool} -- [description] (default: {False})
              observed {bool} -- [description] (default: {False})
  
          Returns:
              [type] -- [description]