code: def test_canonical_hf_index_retriever_retrieve(self):
      n_docs = 1
      retriever = self.get_dummy_canonical_hf_index_retriever()
      hidden_states = np.array(
          [
              np.ones(self.retrieval_vector_size),
              -np.ones(self.retrieval_vector_size),
          ],
          dtype=np.float32,
      )
      retrieved_doc_embeds, doc_ids, doc_dicts = retriever.retrieve(
          hidden_states, n_docs=n_docs
      )
      self.assertEqual(
          retrieved_doc_embeds.shape,
          (2, n_docs, self.retrieval_vector_size),
      )
      self.assertEqual(len(doc_dicts), 2)
      self.assertEqual(
          sorted(doc_dicts[0]), ["embeddings", "id", "text", "title"]
      )
      self.assertEqual(len(doc_dicts[0]["id"]), n_docs)
      self.assertEqual(
          doc_dicts[0]["id"][0], "1"
      )  # max inner product is reached with second doc
      self.assertEqual(
          doc_dicts[1]["id"][0], "0"
      )  # max inner product is reached with first doc
      self.assertListEqual(doc_ids.tolist(), [[1], [0]])
  
imports: import json
  import os
  import shutil
  import tempfile
  from unittest import TestCase
  from unittest.mock import patch
  import numpy
  from datasets import Dataset
  from transformers import is_faiss_available
  from transformers.models.bart.configuration_bart import BartConfig
  from transformers.models.bart.tokenization_bart import BartTokenizer
  from transformers.models.bert.tokenization_bert import VOCAB_FILES_NAMES
  from transformers.models.dpr.configuration_dpr import DPRConfig
  from transformers.models.dpr.tokenization_dpr import DPRContextEncoderTokenizer, DPRQuestionEncoderTokenizer
  from transformers.models.rag.configuration_rag import RagConfig
  from transformers.models.rag.retrieval_rag import CustomHFIndex, RagRetriever
  from transformers.models.roberta.tokenization_roberta import VOCAB_FILES_NAMES
  from transformers.testing_utils import require_faiss, require_sentencepiece, require_tokenizers, require_torch
label_desc: Use image node_id 9 for calling the RagRetrieverTest obj's underlying member method code with example usage: obj.test_canonical_hf_index_retriever_retrieve() without return types