code: def close_connection(self):
          "Request a connection close from the SMTP session handling instance."
          if self._is_connected:
              self._is_connected = False
              self._command_parser.close_when_done(f close_connection(self):
          "Request a connection close from the SMTP session handling instance."
          if self._is_connected:
              self._is_connected = False
              self._command_parser.close_when_done()
docs: Request a connection close from the SMTP session handling instance.