code: def default():
      return {
          "count": 0,
          "num_preserved_chars": 0,
          "num_dropped_chars": 0,
          "num_non_unk_wordpieces": 0,
          "preserved_ratio": [],
          "dropped_ratio": [],
          "wordpieces": collections.Counter(),
      }
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import apache_beam
  import tensorflow.compat.v1
  from tensorflow_text.python.ops.bert_tokenizer import BertTokenizer
  from tensorflow_text.python.ops.wordpiece_tokenizer import WordpieceTokenizer
  from tensorflow_text.tools.wordpiece_vocab import wordpiece_tokenizer_learner_lib
label_desc: Use image node_id 1 for calling a global function with example usage: default() and returns: dict