Disconnects from the SSDB server

def disconnect(self):
        """
        Disconnects from the SSDB server
        """
        self._parser.on_disconnect()
        if self._sock is None:
            return
        try:
            self._sock.shutdown(socket.SHUT_RDWR)
            self._sock.close()
        except socket.error:
            pass
        self._sock = None