class_docstr: Generative GPT2 Re-rank agent for adding a ClassifierReranker.
code: def get_reranker_class(cls):
      return ClassifierGpt2Reranker
  
imports: from parlai.agents.reranker.reranker import AbstractGpt2RerankAgent
  from parlai.agents.reranker.classifier_reranker import ClassifierReranker
label_desc: Use image node_id 1 for calling the ClassifierGpt2RerankerAgent obj's underlying member method code with example usage: obj.get_reranker_class(cls) and returns: ClassifierGpt2Reranker