Cancels a deferred action with the given id.

    Syntax: {command} <id>

def cmd(send, msg, args):
    """Cancels a deferred action with the given id.

    Syntax: {command} <id>

    """
    try:
        args['handler'].workers.cancel(int(msg))
    except ValueError:
        send("Index must be a digit.")
        return
    except KeyError:
        send("No such event.")
        return
    send("Event canceled.")