def add_rb_timer(signal, period, repeat=0):
    """Add a red-black timer.

    :param int signal: Signal to raise.

    :param int period: The interval (seconds) at which the signal is raised.

    :param int repeat: How many times to send signal. Will stop after ther number is reached.
        Default: 0 - infinitely.

    :rtype: None

    :raises ValueError: If unable to add timer.
    """
