code: def init_output_files(self):
      print("Start: Init Output Files")
      assert (
          len(self.output_training_files) is 0
      ), "Internal storage self.output_files already contains data. This function is intended to be used by the constructor only."
      assert (
          len(self.output_test_files) is 0
      ), "Internal storage self.output_files already contains data. This function is intended to be used by the constructor only."
  
      for i in range(self.n_training_shards):
          name = (
              self.output_name_prefix
              + self.output_training_identifier
              + "_"
              + str(i)
              + self.output_file_extension
          )
          self.output_training_files[name] = []
  
      for i in range(self.n_test_shards):
          name = (
              self.output_name_prefix
              + self.output_test_identifier
              + "_"
              + str(i)
              + self.output_file_extension
          )
          self.output_test_files[name] = []
  
      print("End: Init Output Files")
  
file_path: gluon-nlp/scripts/processing/segment_sentences.py
imports: import statistics
  import nltk
  import multiprocessing
  from collections import defaultdict
  from itertools import islice
  import time
  import os
label_desc: Use image node_id 4 for calling the Sharding obj's underlying member method code with example usage: obj.init_output_files() without return types