class_docstr: Parsing.
class_docstr_tok: ["Parsing","."]
code: def feature_encoders(self, data_dir):
      source_vocab_filename = os.path.join(
          data_dir,
          self.vocab_prefix
          + "_source.vocab.%d" % self.inputs_target_vocab_size,
      )
      target_vocab_filename = os.path.join(
          data_dir,
          self.vocab_prefix
          + "_target.vocab.%d" % self.targets_target_vocab_size,
      )
      source_subtokenizer = text_encoder.SubwordTextEncoder(
          source_vocab_filename
      )
      target_subtokenizer = text_encoder.SubwordTextEncoder(
          target_vocab_filename
      )
      return {
          "inputs": source_subtokenizer,
          "targets": target_subtokenizer,
      }
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import text_encoder
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import registry
  import tensorflow.compat.v1
label_desc: Use image node_id 4 for calling the ParsingEnglishPtb16k obj's underlying member method code with example usage: obj.feature_encoders(data_dir) and returns: dict