class_docstr: Re-ranker object which uses a predictor model to rerank candidates given.
  
  This AbstractReranker can be subclassed to use any classifier or ranking model as
  the predictor.
class_docstr_tok: ["Re-ranker","object","which","uses","a","predictor","model","to","rerank","candidates","given",".","This","AbstractReranker","can","be","subclassed","to","use","any","classifier","or","ranking","model","as","the","predictor","."]
docstr: Get the list of possible predictor classes.
  
  Subclasses must override to return possible classes, given a context string.
docstr_tok: ["Get","the","list","of","possible","predictor","classes",".","Subclasses","must","override","to","return","possible","classes",",","given","a","context","string","."]
code: def get_predictor_label_candidates(
      self, observation: Message, context: str
  ) -> List[str]:
      """
      Get the list of possible predictor classes.
  
      Subclasses must override to return possible classes, given a context string.
      """
  
imports: import logging
  import torch
  from abc import ABC, abstractmethod, abstractclassmethod
  from typing import List, Optional, Tuple
  from parlai.agents.transformer.transformer import TransformerGeneratorAgent
  from parlai.core.agents import create_agent_from_model_file, Agent
  from parlai.core.build_data import modelzoo_path
  from parlai.core.message import Message
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.core.torch_agent import TorchAgent
  from parlai.utils.strings import normalize_reply
  from parlai.utils.torch import argsort
  from parlai.agents.hugging_face.gpt2 import Gpt2Agent
  from projects.msc.agents.long_tga import TransformerVariantAgent
label_desc: Use image node_id 15 for calling the AbstractReranker obj's underlying member method code with example usage: obj.get_predictor_label_candidates(observation, context) without return types