class_docstr: This is the implementation of knowledeagble verbalizer, which uses external knowledge to expand the set of label words.
  This class inherit the ``ManualVerbalizer`` class.
  
  Args:
      tokenizer (:obj:`PreTrainedTokenizer`): The tokenizer of the current pre-trained model to point out the vocabulary.
      classes (:obj:`classes`): The classes (or labels) of the current task.
      prefix (:obj:`str`, optional): The prefix string of the verbalizer.
      multi_token_handler (:obj:`str`, optional): The handling strategy for multiple tokens produced by the tokenizer.
      max_token_split (:obj:`int`, optional):
      verbalizer_lr (:obj:`float`, optional): The learning rate of the verbalizer optimization.
      candidate_frac (:obj:`float`, optional):
docstr: add prefix to label words. For example, if a label words is in the middle of a template,
  the prefix should be ' '.
docstr_tok: ["add","prefix","to","label","words",".","For","example",",","if","a","label","words","is","in","the","middle","of","a","template",",","the","prefix","should","be","'","'","."]
code: def add_prefix(label_words, prefix):
      r"""add prefix to label words. For example, if a label words is in the middle of a template,
      the prefix should be ' '.
      """
      new_label_words = []
      for words in label_words:
          new_label_words.append(
              [prefix + word.lstrip(prefix) for word in words]
          )
      return new_label_words
  
imports: import os
  from openprompt.prompts.manual_template import ManualTemplate
  from transformers.tokenization_utils import PreTrainedTokenizer
  from transformers.utils.dummy_pt_objects import PreTrainedModel
  from openprompt.data_utils import InputFeatures
  import re
  from openprompt.prompts.manual_verbalizer import ManualVerbalizer
  from typing import *
  import torch
  import torch.nn
  import torch.nn.functional
  from openprompt.utils.logging import logger
label_desc: Use image node_id 4 for calling the KnowledgeableVerbalizer obj's underlying member method code with example usage: obj.add_prefix(label_words, prefix) and returns: new_label_words