code: def __init__(self, opt: Opt, shared=None):
      self.init_classifier_layers = opt["init_classifier_layers"]
      self.init_epsilon = opt["init_epsilon"]
      if (
          opt["init_classifier_layers"]
          != "copy_decoder_with_epsilon_noise"
      ):
          self.init_epsilon = 0
      super().__init__(opt, shared)
      self.explicit_classifier_norm = opt["explicit_classifier_norm"]
      self.explicit_classifier_norm_coeff = opt[
          "explicit_classifier_norm_coeff"
      ]
      self.train_mixing_weights = opt["train_mixing_weights"]
      self.use_one_plus_gamma_variant = opt[
          "use_one_plus_gamma_variant"
      ]
      self.train_gamma = opt["train_gamma"]
      self.infer_gamma = opt["infer_gamma"]
      self.pos_class_weight = opt["pos_class_weight"]
  
      assert opt[
          "beam_block_full_context"
      ], "must set --beam-block-full-context True to use PACER"
      assert (
          opt["rag_model_type"] == "token"
      ), "compute_loss not supporting other rag model type"
  
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 2 to create a new DirectorFidAgent object from inherited base classes: FidAgent with example: obj = DirectorFidAgent(opt, shared)