code: def _truncate_to_lead_section(example):
      wiki = example["targets"]
      lead_boundary = example["section_boundaries"][0]
      # Concat a new EOS to the lead since the original one gets truncated.
      lead = tf.concat((wiki[:lead_boundary], [text_encoder.EOS_ID]), 0)
      return lead
  
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 2 for calling a global function with example usage: _truncate_to_lead_section(example) and returns: lead