class_docstr: Problem spec for parsing tokenized Icelandic text to constituency trees.
code: def feature_encoders(self, data_dir):
      source_vocab_filename = os.path.join(
          data_dir,
          "ice_source.tokens.vocab.%d" % self.source_vocab_size,
      )
      target_vocab_filename = os.path.join(
          data_dir,
          "ice_target.tokens.vocab.%d" % self.targeted_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 generator_utils
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import text_encoder
  from tensor2tensor.data_generators import text_problems
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import registry
label_desc: Use image node_id 6 for calling the ParsingIcelandic16k obj's underlying member method code with example usage: obj.feature_encoders(data_dir) and returns: dict