code: def mask(self) -> str:
      return RobertaBase.SUBWORD_PREFIX + self.tokenizer.mask_token
  
imports: import abc
  import numpy
  from pathlib import Path
  from typing import Any, Callable, List, Optional, Tuple, Union
  import tensorflow
  import transformers
  from transformers import TFAutoModelForMaskedLM, AutoTokenizer
label_desc: Use image node_id 2 for calling the RobertaBase obj's underlying member method code with example usage: obj.mask() and returns: unknown