@classmethod
def __normalize_chapters(cls, n, element):
    if isinstance(element, HtmlElement):
        return n(element.get('href'))
    if isinstance(element, str):
        return n(element)
    return element
@classmethod
def __normalize_chapters(cls, n, element):
    if isinstance(element, HtmlElement):
        return n(element.get('href'))
    if isinstance(element, str):
        return n(element)
    return element