code: def all_contents(self):
          '''Iterator over all contents'''
          translations_iterator = chain(*self.translations_lists())
          return chain(translations_iterator,
                       *(pair[i] for pair in self.contents_list_pairs()
                         for i in (0, 1))f all_contents(self):
          '''Iterator over all contents'''
          translations_iterator = chain(*self.translations_lists())
          return chain(translations_iterator,
                       *(pair[i] for pair in self.contents_list_pairs()
                         for i in (0, 1)))
docs: Iterator over all contents