Returns HTML tag representing specific header for this element.

        :Returns:
          String representation of HTML tag.

def get_header(self, elem, style, node):
        """Returns HTML tag representing specific header for this element.

        :Returns:
          String representation of HTML tag.

        """
        font_size = style
        if hasattr(elem, 'possible_header'):
            if elem.possible_header:
                return 'h1'

        if not style:
            return 'h6'

        if hasattr(style, 'style_id'):
            font_size = _get_font_size(self.doc, style)

        try:
            if font_size in self.doc.possible_headers_style:
                return 'h{}'.format(self.doc.possible_headers_style.index(font_size)+1)

            return 'h{}'.format(self.doc.possible_headers.index(font_size)+1)
        except ValueError:
            return 'h6'