def time_to_string(seconds):
    """transforms 3600 to 01:00:00 and 48610 to 13:30:10, reversing the parse_time function.

    Examples:
        time_to_string(48600) = 13:30:00
        time_to_string(3600) = 01:00:00"""

    hours = seconds / 3600
    minutes = (hours - int(hours)) * 60
    seconds = seconds % 60
    # now to strings
    hours = str(int(hours)).zfill(2)
    minutes = str(int(minutes)).zfill(2)
    seconds = str(int(seconds)).zfill(2)
    return "{}:{}:{}".format(hours, minutes, seconds)