def time_string(seconds):
    """Returns time in seconds as a string formatted HHHH:MM:SS."""
    s = int(round(seconds))  # round to nearest second
    h, s = divmod(s, 3600)  # get hours and remainder
    m, s = divmod(s, 60)  # split remainder into minutes and seconds
    return "%2i:%02i:%02i" % (h, m, s)