code: def save_source_vocabs(source_vocabs: List[Vocab], folder: str):
      
      for i, vocab in enumerate(source_vocabs):
          vocab_to_json(vocab, os.path.join(folder, C.VOCAB_SRC_NAME % i))
docs: Saves source vocabularies (primary surface form vocabulary) and optional factor vocabularies to folder.
  
      :param source_vocabs: List of source vocabularies.
      :param folder: Destination folder.