def dated(zelf):
    """ retrieve the creation time of an object. """
    val = ''
    if 'Date' in zelf:
        val = zelf.Date
    elif 'date' in zelf:
        val = zelf.date
    elif 'published' in zelf:
        val = zelf.published
    elif 'added' in zelf:
        val = zelf.added
    elif 'saved' in zelf:
        val = zelf.saved
    elif 'timed' in zelf:
        val = zelf.timed
    return val
