code: def on_response(
      self, response: ResponseDelegate, db_row: DatabaseRow
  ):
      query = response.request.query
      choices = response.cvalues
  
      corpus = [self.tokenize(choice) for choice in choices]
      bm25 = BM25Okapi(corpus)
      ranks = np.argsort(bm25.get_scores(self.tokenize(query)))[::-1]
  
      reranked_choices = [response.choices[rank] for rank in ranks]
      response.choices = reranked_choices
  
      response.choices = response.choices[:50]
  
imports: from nboost.plugins import Plugin
  from nboost.delegates import ResponseDelegate
  from nboost.database import DatabaseRow
  import numpy
  from multiprocessing import Pool, cpu_count
  import math
  from nltk.stem import PorterStemmer
  from nltk.tokenize import word_tokenize
  from nltk.corpus import stopwords
  import nltk
label_desc: Use image node_id 2 for calling the PrerankPlugin obj's underlying member method code with example usage: obj.on_response(response, db_row) without return types