class_docstr: Builder type to hide complex configuration of PTL Trainers for Megatron LLM models.
  Can be extended to change behavior for a specific model.
code: def __init__(self, cfg: DictConfig) -> None:
      self.cfg = cfg
  
imports: import sys
  from typing import Union
  from omegaconf import DictConfig
  from pytorch_lightning import Trainer
  from pytorch_lightning.callbacks import ModelSummary
  from pytorch_lightning.plugins.environments import TorchElasticEnvironment
  from nemo.collections.nlp.parts.nlp_overrides import CustomProgressBar, GradScaler, MegatronHalfPrecisionPlugin, NLPDDPStrategy, NLPDDPStrategyNotebook, NLPFSDPStrategy, PipelineMixedPrecisionPlugin
  from nemo.utils import logging
label_desc: Use image node_id 1 to create a new MegatronTrainerBuilder object  with example: obj = MegatronTrainerBuilder(cfg)