code: def get_code(self):
          
          code = UNKNOWN
          for result in self._results:
              if code == UNKNOWN or (result.code < UNKNOWN
                                     and result.code > code):
                  code = result.code
          return code
docs: the final code for multi-checks
  
          arguments:
              the worst-case code from all added results,
              or UNKNOWN if none were added