docstr: Refactored Decode, RAG-Style to split the FID.decoder into
  decoder_output_before_final_projection + decoder_output.
  
  :param input:
      input for the decoder
  :param encoder_states:
      RAG encoder states
  :param incr_state:
      incremental decoder state
  
  :return (output, new_incr_state):
      return the output token distribution, as well as new incremental state.
docstr_tok: ["Refactored","Decode",",","RAG-Style","to","split","the","FID.decoder","into","decoder_output_before_final_projection","+","decoder_output",".",":","param","input",":","input","for","the","decoder",":","param","encoder_states",":","RAG","encoder","states",":","param","incr_state",":","incremental","decoder","state",":","return","(","output",",","new_incr_state",")",":","return","the","output","token","distribution",",","as","well","as","new","incremental","state","."]
code: def decoder(
      self,
      input: torch.LongTensor,
      encoder_states: Tuple[Any, ...],
      incr_state: Optional[Dict[str, Any]] = None,
  ) -> Tuple[torch.Tensor, Optional[Dict[str, Any]]]:
      """
      Refactored Decode, RAG-Style to split the FID.decoder into
      decoder_output_before_final_projection + decoder_output.
  
      :param input:
          input for the decoder
      :param encoder_states:
          RAG encoder states
      :param incr_state:
          incremental decoder state
  
      :return (output, new_incr_state):
          return the output token distribution, as well as new incremental state.
      """
  
      dec_out, incr_state = self.decoder_output_before_final_projection(
          input, encoder_states
      )
      dec_out = self.decoder_output(dec_out, encoder_states)
      return dec_out, incr_state
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from typing import Optional, Any, Dict, Tuple, Union, List
  from abc import abstractmethod
  from parlai.agents.transformer.modules import TransformerDecoderLayer
  from parlai.agents.fid.fid import FidAgent, FidModel
  from parlai.core.message import Message
  from parlai.core.metrics import AverageMetric
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.core.torch_generator_agent import PPLMetric
  from parlai.core.torch_agent import Batch, DictionaryAgent
  import parlai.utils.logging
  from projects.blenderbot2.agents.blenderbot2 import BlenderBot2FidAgent, BlenderBot2FidModel, T5BlenderBot2FidModel
  from parlai.agents.fid.fid import WizIntGoldDocRetrieverFiDAgent
  import parlai.agents.transformer.modules.ffn
  from parlai.agents.transformer.modules import LAYER_NORM_EPS
label_desc: Use image node_id 9 for calling the DirectorFidModelMixin obj's underlying member method code with example usage: obj.decoder(input, encoder_states, incr_state) and returns: dec_out,  incr_state