code: async def quit(self, timeout: DefaultNumType = _default) -> SMTPResponse:
          
          # Can't quit without HELO/EHLO
          await self._ehlo_or_helo_if_needed()
  
          async with self._command_lock:
              response = await self.execute_command(b"QUIT", timeout=timeout)
          if response.code != SMTPStatus.closing:
              raise SMTPResponseException(response.code, response.message)
  
          self.close()
  
          return response
docs: Send the SMTP QUIT command, which closes the connection.
          Also closes the connection from our side after a response is received.
  
          :raises SMTPResponseException: on unexpected server response code