docs: def find_date(url):
      "Extract date from URL page if exists."
      def _clean_split(div_str):
          sl = []
          for div in div_str.split('/'):
              div = div.strip().lower()
              if div != '':
                  sl.append(div)
          return sl
          
      url_path = find_path(url)
      url_path_parts = _clean_split(url_path)
      date_parts = []
      for part in url_path_parts:
          try:
              _dateparse(part) # is part date-like?
              date_parts.append(part)
          except ValueError:
              continue
      if len(date_parts) == 0:
          return
      date_str = '/'.join(date_parts)
      return _dateparse(date_str)