def reliability_calc(RACC, ACC):
    """
    Calculate Reliability.

    :param RACC: random accuracy
    :type RACC: float
    :param ACC: accuracy
    :type ACC: float
    :return: reliability as float
    """
    try:
        result = (ACC - RACC) / (1 - RACC)
        return result
    except Exception:
        return "None"