class_docstr: Transforms an input by replacing its words with antonym provided by WordNet.
  Download nltk_data before running.
  
  Just support adj pos word antonym replace.
code: def __repr__(self):
      return "SwapAntWordNet"
  
imports: from ...transformation import WordSubstitute
label_desc: Use image node_id 2 for calling the SwapAntWordNet obj's underlying member method code with example usage: obj.__repr__() and returns: str