class_docstr: A class implementing the chatbot problem for the OpenSubtitles dataset.
  
  http://opus.nlpl.eu/OpenSubtitles-v2018.php
class_docstr_tok: ["A","class","implementing","the","chatbot","problem","for","the","OpenSubtitles","dataset",".","http",":","\/\/opus.nlpl.eu\/OpenSubtitles-v2018.php"]
docstr: Clean a line with some regex rules.
  
  Args:
    line: string, line to be processed and returned
  
  Returns:
    string
docstr_tok: ["Clean","a","line","with","some","regex","rules",".","Args",":","line",":","string",",","line","to","be","processed","and","returned","Returns",":","string"]
code: def clean_line(self, line):
      """Clean a line with some regex rules.
  
      Args:
        line: string, line to be processed and returned
  
      Returns:
        string
      """
  
      line = line.lower()
      line = re.sub("[^a-z .!?'\t\\\\]", "", line)
      line = re.sub("\\\\['] ", " '", line)
      line = re.sub("[\\\\]", " ", line)
      line = re.sub("[.]", " . ", line)
      line = re.sub("[?]", " ? ", line)
      line = re.sub("[!]", " ! ", line)
      line = re.sub("[ ]'[ ]", " ", line)
      line = re.sub("n't", " n't", line)
  
      return line
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import os
  import re
  import zipfile
  from tensor2tensor.data_generators import dialog_abstract
  from tensor2tensor.data_generators import text_encoder
  from tensor2tensor.utils import registry
label_desc: Use image node_id 6 for calling the DialogOpensubtitles64k2009 obj's underlying member method code with example usage: obj.clean_line(line) and returns: line