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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def create_title(article, language, title, slug=None, description=None, page_title=None, menu_title=None, meta_description=None, creation_date=None, image=None):
 """ Create an article title. """

    # validate article
    assert isinstance(article, Article)

    # validate language:
    assert language in get_language_list(article.tree.node.site_id)

    # validate creation date
    if creation_date:
        assert isinstance(creation_date, datetime.date)

    # set default slug:
    if not slug:
        slug = settings.CMS_ARTICLES_SLUG_FORMAT.format(
            now=creation_date or now(),
            slug=slugify(title),
        )

    # find unused slug:
    base_slug = slug
    qs = Title.objects.filter(language=language)
    used_slugs = list(s for s in qs.values_list('slug', flat=True) if s.startswith(base_slug))
    i = 1
    while slug in used_slugs:
        slug = '%s-%s' % (base_slug, i)
        i += 1

    # create title
    title = Title.objects.create(
        article=article,
        language=language,
        title=title,
        slug=slug,
        description=description,
        page_title=page_title,
        menu_title=menu_title,
        meta_description=meta_description,
        image=image,
    )

    return title