code: def _create_text_fragments(self, pairs):
          
          self.log(u"Creating TextFragment objects")
          text_filter = self._build_text_filter()
          for pair in pairs:
              self.add_fragment(
                  TextFragment(
                      identifier=pair[0],
                      lines=pair[1],
                      filtered_lines=text_filter.apply_filter(pair[1])
                  )
              )
docs: Create text fragment objects and append them to this list.
  
          :param list pairs: a list of pairs, each pair being (id, [line_1, ..., line_n])