code: def _get_subinfo_list(self, videoname):
          
          # searching subtitles
          res = self.session.get(self.API, params={'q': videoname})
          doc = res.content
          referer = res.url
          subgroups = self._parse_search_results_html(doc)
          if not subgroups:
              return []
          subgroup = self._filter_subgroup(subgroups)
  
          # get subtitles
          headers = {
              'Referer': referer
          }
          res = self.session.get(self._join_url(self.API, subgroup['link']), headers=headers)
          doc = res.content
          referer = res.url
          subinfo_list = self._parse_sublist_html(doc)
          for subinfo in subinfo_list:
              subinfo['link'] = self._join_url(res.url, subinfo['link'])
          return subinfo_list, referer
docs: return subinfo_list of videoname