class_docstr: Combo GPT2 Agent.
  
  This agent can handle retrieval for some contexts, and vanilla decoder-only
  computation for others.
class_docstr_tok: ["Combo","GPT2","Agent",".","This","agent","can","handle","retrieval","for","some","contexts",",","and","vanilla","decoder-only","computation","for","others","."]
code: def get_retrieved_knowledge(self, message: Message) -> List[Document]:
      if message.get("skip_retrieval"):
          return []
      return super().get_retrieved_knowledge(message)
  
imports: from typing import Optional, Tuple, List, Union
  import torch
  import torch.nn
  from parlai.agents.fid.fid import FidModel, FidAgent, SearchQuerySearchEngineFiDAgent, WizIntGoldDocRetrieverFiDAgent
  from parlai.agents.hugging_face.gpt2 import Gpt2Agent
  from parlai.agents.rag.rag import BaseGenerationAgentMixin
  from parlai.agents.rag.retrievers import Document
  from parlai.core.dict import DictionaryAgent
  from parlai.core.message import Message
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.core.torch_agent import Batch, Output
  from parlai.core.torch_generator_agent import TorchGeneratorAgent
  from parlai.utils.torch import padded_tensor
  from projects.seeker.agents.seeker import SeekerAgent
  from projects.seeker.agents.gpt2_seeker_modules import GPT2WithRetrieverModel, ComboGPT2Model
label_desc: Use image node_id 6 for calling the GPT2ComboAgent obj's underlying member method code with example usage: obj.get_retrieved_knowledge(message) and returns: super, list