docs: def get_title_tags(index_page):
      """
      Collect data from all the functions defined in this module and return list
      of titles parsed from HTML, ``<meta>`` tags and dublin core inlined in
      ``<meta>`` tags.
  
      Args:
          index_page (str): HTML content of the page you wish to analyze.
  
      Returns:
          list: List of :class:`.SourceString` objects.
      """
      dom = dhtmlparser.parseString(index_page)
  
      titles = [
          get_html_titles(dom),
          get_html_meta_titles(dom),
          get_dublin_core_titles(dom),
      ]
  
      return sum(titles, [])