class_docstr: Test retrieval methods for BB2 with FiD.
class_docstr_tok: ["Test","retrieval","methods","for","BB2","with","FiD","."]
code: def test_retrieval_classify(self):
      _test_bb2_fid(
          KnowledgeAccessMethod.CLASSIFY,
          query_generator_model_file=SEARCH_QUERY_MODEL,
      )
  
imports: import copy
  import torch.cuda
  import unittest
  from parlai.core.agents import create_agent
  import parlai.utils.testing
label_desc: Use image node_id 4 for calling the TestBB2Fid obj's underlying member method code with example usage: obj.test_retrieval_classify() without return types