def show_taglist(obj):
    """Additional prompt to show unique tag list.

    Parameters
    ----------
    obj : BukuDb instance
        A valid instance of BukuDb class.
    """
    unique_tags, dic = obj.get_tag_all()
    if not unique_tags:
        count = 0
        print('0 tags')
    else:
        count = 1
        for tag in unique_tags:
            print('%6d. %s (%d)' % (count, tag, dic[tag]))
            count += 1
        print()
