@staticmethod
def _get_chapter_size(soup):
    """Return the size of a chapter

        The size is found based on the number of <option> tags within a
        specific <select> tag.
        """
    select_tag = soup.find('select', {'id': 'single-pager', 'class':
        'selectpicker'})
    return sum(1 for option in select_tag.findAll('option'))
