def forward(server, command, args):
    """
    Forward a command to all slaves.

    :param server: The ``SubwayDaemon`` instance.
    :param command: The command to forward.
    :param args: Any arguments to provide for the command.  These
                 arguments must already be constructed as a single
                 string; note that Turnstile uses the colon character
                 (":") as an argument separator.
    """
    channel = server.config.get('channel', 'control')
    message = command
    if args:
        message += ':%s' % args
    for slave in server.slaves:
        slave.publish(channel, message)
