class_docstr: GPT2 with Retriever Model.
  
  A GPT2 model that receives documents from a retriever.
class_docstr_tok: ["GPT2","with","Retriever","Model",".","A","GPT2","model","that","receives","documents","from","a","retriever","."]
code: def _tie_weights(self, output_embeddings, input_embeddings):
      output_embeddings.weight = input_embeddings.weight
  
imports: from typing import Optional, Type, Tuple, List, Dict, Any
  import torch
  import torch.nn
  from parlai.agents.fid.fid import FidModel, concat_enc_outs
  from parlai.agents.hugging_face.gpt2 import GPT2Decoder, Gpt2Agent
  from parlai.agents.rag.args import RetrieverType
  from parlai.agents.rag.modules import RagModel
  from parlai.agents.rag.retrievers import Document, BLANK_DOC, SearchQuerySearchEngineRetriever, retriever_factory, RagRetriever
  from parlai.core.dict import DictionaryAgent
  from parlai.core.opt import Opt
  import parlai.utils.logging
  from projects.seeker.agents.seeker_modules import ComboFidSearchQuerySearchEngineRetriever
  from projects.seeker.agents.seeker_modules import combo_fid_retriever_factory, interleave_fid_combo_outputs, ComboFidModel
label_desc: Use image node_id 10 for calling the GPT2WithRetrieverModel obj's underlying member method code with example usage: obj._tie_weights(output_embeddings, input_embeddings) without return types