code: def _handle_run_exception(self, exc):
          
          if len(self._current_tups) == 1:
              tup = self._current_tups[0]
              self.raise_exception(exc, tup)
              if self.auto_fail:
                  self.fail(tup)
docs: Process an exception encountered while running the ``run()`` loop.
  
          Called right before program exits.