class_docstr: Customtokenizer which will tokenize the input text as words or phases and convert the words (str) to an index (int) using the vocab.
  If you would like tokens, please use `hub.BertTokenizer`.
docstr: Converts a sequence of tokens (string) in a single string. 
docstr_tok: ["Converts","a","sequence","of","tokens","(","string",")","in","a","single","string","."]
code: def convert_tokens_to_string(self, tokens: List[str]):
      """Converts a sequence of tokens (string) in a single string."""
      if self.tokenize_chinese_chars:
          out_string = "".join(tokens).strip()
      else:
          out_string = " ".join(tokens).strip()
      return out_string
  
imports: import collections
  import inspect
  import os
  from typing import Callable, List, Union
  import paddlehub
  from paddlehub.utils.log import logger
  from paddlehub.text.bert_tokenizer import BasicTokenizer
  from paddlehub.text.utils import load_vocab, whitespace_tokenize
label_desc: Use image node_id 6 for calling the CustomTokenizer obj's underlying member method code with example usage: obj.convert_tokens_to_string(tokens) and returns: out_string