Shutdown listening socket

        :rtype: None

def _shutdown_listen_socket(self):
        """
        Shutdown listening socket

        :rtype: None
        """
        self.debug("()")
        if self._listen_socket in self._listening:
            self._listening.remove(self._listen_socket)
        if self._listen_socket:
            self._listen_socket.close()
        self._listen_socket = None