def get_elapsed_time_string(start_time, end_time):
    """
    Get a string representing the elapsed time given a start and end time.
    :param start_time: Start time (time.time())
    :param end_time: End time (time.time())
    :return:
    """
    elapsed = end_time - start_time
    hours = str(int(elapsed / 3600))
    elapsed = elapsed - elapsed / 3600
    mins = str(int(elapsed / 60))
    secs = str(int(elapsed) % 60)
    time_string = hours + ' HOURS ' + mins + ' MINS ' + secs + ' SECS.'
    return time_string
