class_docstr: Processor for the SQuAD data set.
  used by the version 1.1 and version 2.0 of SQuAD, respectively.
  
  Args:
      data_file: data file path
      mode: TRAINING_MODE/EVALUATION_MODE/INFERENCE_MODE for creating training/evaluation/inference dataset
code: def __init__(self, data_file: str, mode: str):
      self.data_file = data_file
      self.mode = mode
      # Memoizes documents to reduce memory use (as the same document is often used for many questions)
      self.doc_id = 0
      self.context_text_to_doc_id = {}
      self.doc_id_to_context_text = {}
  
imports: import collections
  from typing import List
  import ijson
  import numpy
  from transformers.models.bert.tokenization_bert import BasicTokenizer
  from nemo.collections.nlp.data.data_utils import DataProcessor, check_chinese_char, normalize_answer, normalize_chinese_answer
  from nemo.utils import logging
label_desc: Use image node_id 1 to create a new SquadProcessor object from inherited base classes: DataProcessor with example: obj = SquadProcessor(data_file, mode)