def rand_block(minimum, scale, maximum=1):
    """
        block current thread at random pareto time ``minimum < block < 15`` and return the sleep time ``seconds``

    :param minimum:
    :type minimum:
    :param scale:
    :type scale:
    :param slow_mode: a tuple e.g.(2, 5)
    :type slow_mode: tuple
    :return:
    """
    t = min(rand_pareto_float(minimum, scale), maximum)
    time.sleep(t)
    return t
block current thread at random pareto time ``minimum < block < 15`` and return the sleep time ``seconds``

    :param minimum:
    :type minimum:
    :param scale:
    :type scale:
    :param slow_mode: a tuple e.g.(2, 5)
    :type slow_mode: tuple
    :return: