code: def unregistercls(self, schemacls=None, data_types=None):
          
          if schemacls is not None:
  
              # clean schemas by data type
              for data_type in list(self._schbytype):
                  _schemacls = self._schbytype[data_type]
                  if _schemacls is schemacls:
                      del self._schbytype[data_type]
  
          if data_types is not None:
  
              for data_type in data_types:
                  if data_type in self._schbytype:
                      del self._schbytype[data_type]
docs: Unregister schema class or associated data_types.
  
          :param type schemacls: sub class of Schema.
          :param list data_types: data_types to unregister.