code: def _modify_config(retro_cfg, cfg, add_cfg_to_tree=False):
      """
      This function modifies the original retro pre-training config with attributes from the finetuning config (cfg).
      The `add_cfg_to_tree` arg adds `cfg` to the top of the yaml tree which is needed for all `hparams.yaml` files when passed as an arg to `load_from_checkpoint()`.
      """
      OmegaConf.set_struct(retro_cfg, True)
      with open_dict(retro_cfg):
          retro_cfg.megatron_amp_O2 = cfg.model.get(
              "megatron_amp_O2", False
          )
          retro_cfg.data = cfg.model.data
          retro_cfg.precision = cfg.trainer.precision
          retro_cfg.optim = cfg.model.optim
          retro_cfg.micro_batch_size = cfg.model.micro_batch_size
          # This is needed when modifying a hparam file directly to load `.ckpt` files.
          # This is not needed to modify the cfg in `.nemo` files.
          if add_cfg_to_tree:
              OmegaConf.resolve(retro_cfg)
              retro_cfg.cfg = retro_cfg
      return retro_cfg
  
file_path: NeMo/examples/nlp/language_modeling/megatron_retro_fine_tune.py
imports: import datetime
  import os
  from omegaconf.omegaconf import OmegaConf, open_dict
  from pytorch_lightning import Trainer
  from pytorch_lightning.callbacks.timer import Timer
  from pytorch_lightning.plugins.environments import TorchElasticEnvironment
  from pytorch_lightning.plugins.precision import MixedPrecisionPlugin
  from pytorch_lightning.trainer.connectors.checkpoint_connector import _CheckpointConnector
  from nemo.collections.nlp.models.language_modeling.megatron_retro_fine_tune_model import MegatronRetroFinetuneModel
  from nemo.collections.nlp.parts.nlp_overrides import CustomProgressBar, GradScaler, MegatronHalfPrecisionPlugin, NLPDDPStrategy, NLPSaveRestoreConnector
  from nemo.core.config import hydra_runner
  from nemo.utils import logging
  from nemo.utils.exp_manager import StatelessTimer, exp_manager
label_desc: Use image node_id 1 for calling a global function with example usage: _modify_config(retro_cfg, cfg, add_cfg_to_tree) and returns: retro_cfg