docs: def get_dc_keywords(index_page):
      """
      Return list of `keywords` parsed from Dublin core.
  
      Args:
          index_page (str): Content of the page as UTF-8 string
  
      Returns:
          list: List of :class:`.SourceString` objects.
      """
      keyword_lists = (
          keyword_list.split()
          for keyword_list in parse_meta(index_page, "dc.keywords", "DC")
      )
  
      return [
          SourceString(keyword, source="DC")
          for keyword in sum(keyword_lists, [])  # flattern the list
      ]