code: def test_char_cut_tf_str(self):
      t_sen_in = tf.placeholder(dtype=tf.string, shape=())
      t_sen_out = char_cut_tf(t_sen_in)
      with self.cached_session(use_gpu=False, force_gpu=False) as sess:
          sen_out = sess.run(t_sen_out, {t_sen_in: "我爱北京天安门"})
          logging.info(sen_out.decode("utf-8"))
          self.assertEqual("我 爱 北 京 天 安 门", sen_out.decode("utf-8"))
  
imports: import os
  from pathlib import Path
  import delta.compat
  from absl import logging
  import tempfile
  import numpy
  from delta import PACKAGE_ROOT_DIR
  from delta import utils
  from delta.data.preprocess.text_ops import clean_english_str_tf
  from delta.data.preprocess.text_ops import char_cut_tf
  from delta.data.preprocess.text_ops import tokenize_label
  from delta.data.preprocess.text_ops import tokenize_sentence
  from delta.data.preprocess.text_ops import process_one_label_dataset
  from delta.data.preprocess.text_ops import process_multi_label_dataset
label_desc: Use image node_id 5 for calling the TextOpsTest obj's underlying member method code with example usage: obj.test_char_cut_tf_str() without return types