def hms_string(sec_elapsed):
    """Utility to get the hour:minute:seceonds for an 
       elapsed period in seconds"""
    h = int(sec_elapsed / (60 * 60))
    m = int(sec_elapsed % (60 * 60) / 60)
    s = sec_elapsed % 60
    return '%02d:%02d:%02d' % (h, m, s)
