code: def _add_retro_args(parser):
      group = parser.add_argument_group(title="retro")
  
      group.add_argument(
          "--retro-workdir",
          default=None,
          help="Retro working directory, which contains the "
          "preprocessed data for for pretraining. This directory "
          "is built during preprocessing (see "
          "tools/retro/README.md), and contains subdirectories "
          "for the chunk database and pretraining neighbors.",
      )
      group.add_argument(
          "--retro-add-retriever",
          action="store_true",
          default=False,
          help="Add a retriever to the transformer, for use in "
          "pretraining a Retro model.",
      )
      group.add_argument(
          "--retro-cyclic-train-iters",
          type=int,
          default=None,
          help="Set number of training iterations for cyclic "
          "Retro training.",
      )
      group.add_argument(
          "--retro-encoder-layers",
          type=int,
          default=2,
          help="Number of layers to use for the retrieval " "encoder.",
      )
      group.add_argument(
          "--retro-encoder-hidden-dropout",
          type=float,
          default=0.1,
          help="Hidden dropout for " "retrieval encoder.",
      )
      group.add_argument(
          "--retro-encoder-attention-dropout",
          type=float,
          default=0.1,
          help="Attention dropout for " "retrieval encoder.",
      )
      group.add_argument(
          "--retro-num-neighbors",
          type=int,
          default=2,
          help="Number of neighbors to retrieve during " "pretraining.",
      )
      group.add_argument(
          "--retro-num-retrieved-chunks",
          type=int,
          default=2,
          help="Number of chunks to retrieve from the retrieval "
          "database.",
      )
      group.add_argument(
          "--retro-return-doc-ids",
          action="store_true",
          help="Turn this on when preprocessing retro data.",
      )
      group.add_argument(
          "--retro-attention-gate",
          type=float,
          default=1,
          help="Gated cross attention.",
      )
      group.add_argument(
          "--retro-no-verify-neighbor-count",
          action="store_false",
          dest="retro_verify_neighbor_count",
          help="Skip verifying that len(GPT dataset) == len(saved "
          "neighbors).",
      )
  
      # Enforce argument naming convention.
      for action in group._group_actions:
          prefix = action.dest.split("_")[0]
          assert prefix == "retro", (
              "Retro args must be prefixed with '--retro-*', for consistent "
              "styling. Please fix '%s'."
              % ", ".join(action.option_strings)
          )
  
      return parser
  
imports: import argparse
  import dataclasses
  import json
  import os
  import torch
  import types
  import torch.nn.functional
  from megatron.global_vars import set_retro_args, get_retro_args
  from tools.retro.utils import get_args_path
  from megatron.core.models.retro import RetroConfig
  from megatron.core.transformer import TransformerConfig
label_desc: Use image node_id 8 for calling a global function with example usage: _add_retro_args(parser) and returns: parser