class_docstr: Base class for Wikisum problems.
class_docstr_tok: ["Base","class","for","Wikisum","problems","."]
code: def feature_encoders(self, data_dir):
      vocab_filename = os.path.join(data_dir, self.vocab_filename)
      encoder = text_encoder.SubwordTextEncoder(vocab_filename)
      # Shared encoder for inputs and targets
      return {"inputs": encoder, "targets": encoder}
  
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 4 for calling the WikisumBase obj's underlying member method code with example usage: obj.feature_encoders(data_dir) and returns: dict