code: def _process_sentence(self, sentence):
      return (
          self.start_token
          + " "
          + sentence.string.strip()
          + " "
          + self.end_token
      )
  
imports: from typing import Tuple
  from spacy.pipeline.pipes import Language
label_desc: Use image node_id 3 for calling the BertPreprocessor obj's underlying member method code with example usage: obj._process_sentence(sentence) and returns: unknown