def _get_heading_level(self, element):
        """
        Returns the level of heading.

        :param element: The heading.
        :type element: hatemile.util.html.htmldomelement.HTMLDOMElement
        :return: The level of heading.
        :rtype: int
        """
        # pylint: disable=no-self-use

        tag = element.get_tag_name()
        if tag == 'H1':
            return 1
        elif tag == 'H2':
            return 2
        elif tag == 'H3':
            return 3
        elif tag == 'H4':
            return 4
        elif tag == 'H5':
            return 5
        elif tag == 'H6':
            return 6
        return -1
Returns the level of heading.

        :param element: The heading.
        :type element: hatemile.util.html.htmldomelement.HTMLDOMElement
        :return: The level of heading.
        :rtype: int