def METHOD_NAME(self):
    try:
        lock_socket = register_socket(self.tag) # the check is ~200000 faster and more reliable than checking via 'netstat' or 'ps' etc.
        lock_socket.shutdown(socket.SHUT_RDWR)
        lock_socket.close()
    except socket.error: # Unix socket in use
        return True
    sleep(0.5)
    # Unix socket is not used, but maybe it's old version of daemon not using socket
    return bool(self.get_pid_by_listening_port())