class_docstr: Wikipedia references->lead section summarization task.
class_docstr_tok: ["Wikipedia","references-",">","lead","section","summarization","task","."]
code: def preprocess_example(self, example, mode, hparams):
      example["targets"] = _truncate_to_lead_section(example)
      return super(
          WikisumCommoncrawlLeadSection, self
      ).preprocess_example(example, mode, hparams)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import json
  import math
  import os
  import re
  import string
  import tempfile
  import six
  from tensor2tensor.data_generators import generator_utils
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import text_encoder
  from tensor2tensor.data_generators import tokenizer
  from tensor2tensor.data_generators.wikisum import utils
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import metrics
  from tensor2tensor.utils import registry
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling the WikisumCommoncrawlLeadSection obj's underlying member method code with example usage: obj.preprocess_example(example, mode, hparams) and returns: super