def get_runtime(sec):
    """
    Get the runtime in hour:minute:second.

    Args:
        sec (float): Runtime in seconds.
    
    Return:
        str for the formatted runtime.
    """
    hour = sec // 3600
    sec %= 3600
    minute = sec // 60
    sec %= 60
    return "%d:%02d:%02d" % (hour, minute, sec)