code: def test_demo(self):
      # related to issue https://github.com/fastnlp/fastNLP/issues/324#issue-705081091
      from fastNLP import DataSet, Instance
      from fastNLP.io import DataBundle
  
      data_bundle = DataBundle()
      ds = DataSet()
      ds.append(Instance(raw_words="截流 进入 最后 冲刺 （ 附 图片 １ 张 ）"))
      data_bundle.set_dataset(ds, name="train")
      data_bundle = CWSPipe().process(data_bundle)
      assert "<" not in data_bundle.get_vocab("chars")
  
file_path: fastNLP/tests/io/pipe/test_cws.py
imports: import pytest
  import os
  from fastNLP.io.pipe.cws import CWSPipe
label_desc: Use image node_id 2 for calling the TestCWSPipe obj's underlying member method code with example usage: obj.test_demo() without return types