class_docstr: Question-Answering-based Information Extraction
class_docstr_tok: ["Question-Answering-based","Information","Extraction"]
docstr: check columns
docstr_tok: ["check","columns"]
code: def _check_columns(self, labels, df):
      """check columns"""
      cols = df.columns.values
      for l in labels:
          if l in cols:
              raise ValueError(
                  "There is already a column named %s in your DataFrame."
                  % (l)
              )
  
imports: from transformers import AutoModelForQuestionAnswering, AutoTokenizer, TFAutoModelForQuestionAnswering
  from whoosh import index, qparser
  from whoosh.fields import *
  from whoosh.qparser import QueryParser
  from ...None import utils
  from ...imports import *
  from ...torch_base import TorchBase
  from ..None import preprocessor
  from ..None import textutils
  from itertools import chain, zip_longest
label_desc: Use image node_id 2 for calling the AnswerExtractor obj's underlying member method code with example usage: obj._check_columns(labels, df) without return types