docs: def save(f, arr, vocab):
      """
      Save word embedding file.
      Check :func:`word_embedding_loader.saver.glove.save` for the API.
      """
      f.write(('%d %d' % (arr.shape[0], arr.shape[1])).encode('utf-8'))
      for word, idx in vocab:
          _write_line(f, arr[idx], word)