class_docstr: Add the difference part of aspect to the end of original sentence.
  The difference part is extracted from the training set of SemEval2014
  or user's customization.
  
  Example::
  
      Original sentence: "BEST spicy tuna roll, great asian salad.
      （Target: spicy tuna roll)"
      Transformed sentence: "BEST spicy tuna roll, great asian salad,
      but this small place is packed,
      on a cold day, the seating by the entrance way can be pretty drafty and
      bad service."
docstr: Concatenate the extra part to original sentence.
  
  :param list add_sentence: extra sentence that need to be
      added to original sentence
  :return list: transformed sentence
code: def _concatenate_sentence(self, add_sentence):
      r"""
      Concatenate the extra part to original sentence.
  
      :param list add_sentence: extra sentence that need to be
          added to original sentence
      :return list: transformed sentence
  
      """
      sentence = self.sentence[:-1]
      opi_tag = self.get_postag(add_sentence, 0, 1)
      if opi_tag[0] != "CONJ":
          trans_sentence = self.untokenize(add_sentence)
          if "but" in sentence or "although" in sentence:
              trans_sentence = sentence + "; " + trans_sentence
          else:
              trans_sentence = sentence + ", but " + trans_sentence
      else:
          trans_sentence = self.untokenize(add_sentence)
          trans_sentence = (
              sentence
              + ". "
              + trans_sentence[0].upper()
              + trans_sentence[1:]
          )
      return trans_sentence
  
file_path: textflint/textflint/generation/transformation/ABSA/add_diff.py
imports: import random
  import string
  from .absa_transformation import ABSATransformation
label_desc: Use image node_id 5 for calling the AddDiff obj's underlying member method code with example usage: obj._concatenate_sentence(add_sentence) and returns: trans_sentence