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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _save_vocab_file(vocab_file, subtoken_list):
 """Save subtokens to file."""

  with tf.gfile.Open(vocab_file, mode="w") as f:
    for subtoken in subtoken_list:
      f.write("'%s'\n" % _unicode_to_native(subtoken))