class_docstr: Calculates smoothing coefficient for each language.
code: def add_input(self, accumulator, element):
      _, lang = element
      accumulator["total_count"] += 1
      accumulator["lang_count"].update([lang])
      return accumulator
  
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 3 for calling the CalculateCoefficients obj's underlying member method code with example usage: obj.add_input(accumulator, element) and returns: accumulator