code: def compare(self, statement_a, statement_b):
          
          # Make both strings lowercase
          document_a = self.nlp(statement_a.text.lower())
          document_b = self.nlp(statement_b.text.lower())
  
          statement_a_lemmas = set([
              token.lemma_ for token in document_a if not token.is_stop
          ])
          statement_b_lemmas = set([
              token.lemma_ for token in document_b if not token.is_stop
          ])
  
          # Calculate Jaccard similarity
          numerator = len(statement_a_lemmas.intersection(statement_b_lemmas))
          denominator = float(len(statement_a_lemmas.union(statement_b_lemmas)))
          ratio = numerator / denominator
  
          return ratio
docs: Return the calculated similarity of two
          statements based on the Jaccard index.