def duration_to_string(duration):
    """
    Converts a duration to a string

    Args:
        duration (int): The duration in seconds to convert

    Returns s (str): The duration as a string
    """
    m, s = divmod(duration, 60)
    h, m = divmod(m, 60)
    return '%d:%02d:%02d' % (h, m, s)
