code: def on_train_start(self) -> None:
      super().on_train_start()
      self.init_global_step = self.trainer.global_step
  
file_path: NeMo/nemo/collections/multimodal/models/text_to_image/stable_diffusion/diffusion_model.py
imports: import re
  from abc import ABC, abstractclassmethod
  from typing import Any, Optional
  import torch
  from nemo.core.classes import ModelPT
  from nemo.utils import logging
label_desc: Use image node_id 3 for calling the DiffusionModel obj's underlying member method code with example usage: obj.on_train_start() without return types