docs: def _handle_terminate(self, signal_number, _):
          """Handle a signal to terminate."""
          signal_names = {
              signal.SIGINT: 'SIGINT',
              signal.SIGQUIT: 'SIGQUIT',
              signal.SIGTERM: 'SIGTERM',
          }
          message = 'Terminated by {name} ({number})'.format(
              name=signal_names[signal_number], number=signal_number)
          self._shutdown(message, code=128+signal_number)