code: def _check_operator(self, operator):
          
  
          if not isinstance(operator, type(None)):
              tree = [obj.__name__ for obj in getmro(operator.__class__)]
  
              if not any([parent in tree for parent in self._op_parents]):
                  warn('{0} does not inherit an operator '
                       'parent.'.format(str(operator.__class__)))
docs: Check Set-Up
  
          This method checks algorithm operator against the expected parent
          classes
  
          Parameters
          ----------
          operator : str
              Algorithm operator to check