code: def _verify(self):
          
          scenario_names = [c.scenario.name for c in self._configs]
          if self._scenario_name not in scenario_names:
              msg = ("Scenario '{}' not found.  "
                     'Exiting.').format(self._scenario_name)
              util.sysexit_with_message(msg)
docs: Verify the specified scenario was found and returns None.
  
          :return: None