code: def untranscribed_batch_gen(self):
          
  
          feat_fns = self.corpus.get_untranscribed_fns()
          fn_batches = self.make_batches(feat_fns)
  
          for fn_batch in fn_batches:
              batch_inputs, batch_inputs_lens = utils.load_batch_x(fn_batch,
                                                               flatten=False)
              yield batch_inputs, batch_inputs_lens, fn_batch
docs: A batch generator for all the untranscribed data.