def hh_mm_ss(seconds):
    """
    Converts seconds into hh:mm:ss padded with zeros.
    """
    hh = int(seconds/3600)
    mm = int((seconds % 3600)/60)
    ss = int((seconds % 3600) % 60)
    out = '{hh:02}:{mm:02}:{ss:02}'.format(hh=hh, mm=mm, ss=ss)
    return out