@staticmethod
def getHeadingLevel(bs):
    """
        >>> bsify = lambda html: BeautifulSoup(html, 'html.parser')
        >>> bs = bsify('<h1>Hello</h1>').h1
        >>> TOC.getHeadingLevel(bs)
        1
        >>> bs2 = bsify('<p>Hello</p>').p
        >>> TOC.getHeadingLevel(bs2)

        >>> bs3 = bsify('<article>Hello</article>').article
        >>> TOC.getHeadingLevel(bs3)

        """
    try:
        return int(bs.name[1])
    except (ValueError, IndexError, TypeError):
        return None
