class_docstr: A single training/test example for simple sequence classification.
  
  For examples without an answer, the start and end position are -1.
code: def __init__(
      self,
      qas_id,
      question_text,
      doc_tokens,
      orig_answer_text=None,
      start_position=None,
      end_position=None,
      is_impossible=False,
  ):
      self.qas_id = qas_id
      self.question_text = question_text
      self.doc_tokens = doc_tokens
      self.orig_answer_text = orig_answer_text
      self.start_position = start_position
      self.end_position = end_position
      self.is_impossible = is_impossible
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import json
  import math
  import os
  import random
  import mesh_tensorflow
  import mesh_tensorflow.bert.bert
  import mesh_tensorflow.bert.optimization
  import mesh_tensorflow.bert.tokenization
  import six
  from six.moves import range
  import tensorflow.compat.v1
  from tensorflow.compat.v1 import estimator
label_desc: Use image node_id 1 to create a new SquadExample object from inherited base classes: object with example: obj = SquadExample(qas_id, question_text, doc_tokens, orig_answer_text, start_position, end_position, is_impossible)