code: def search_knn(self, query_vectors, top_k):
      scores, indexes = self.index.search(query_vectors, top_k)
      return scores, indexes
  
imports: import os
  import logging
  import pickle
  import faiss
  import numpy
label_desc: Use image node_id 3 for calling the DenseFlatIndexer obj's underlying member method code with example usage: obj.search_knn(query_vectors, top_k) and returns: scores,  indexes