code: def _wiki_urls_for_shard(shard_id, urls_dir=None):
      """Urls for chunk: dict<str wiki_url, list<str> ref_urls>."""
      urls_dir = urls_dir or WIKI_URLS_DIR
      urls_filepath = os.path.join(urls_dir, WIKI_URLS_FILE % shard_id)
      with tf.gfile.GFile(urls_filepath) as f:
          return json.loads(f.read())
  
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 7 for calling a global function with example usage: _wiki_urls_for_shard(shard_id, urls_dir) and returns: json