root = etree.fromstring(
    """
<root>
    <articles>
        <article type="news">
             <content>some text</content>
        </article>
        <article type="info">
             <content>some text</content>
        </article>
        <article type="news">
             <content>some text</content>
        </article>
    </articles>
</root>
"""
    )
articles = root.find('articles')
поиск элементов по атрибуту с помощью lxml