class_docstr: Set GPU affinity and increase the L2 fetch granularity.
  Adapted from https://github.com/NVIDIA/DeepLearningExamples/tree/master/PyTorch/LanguageModeling/Transformer-XL
code: def setup(
      self, trainer: Trainer, pl_module: LightningModule, stage=None
  ) -> None:
      set_affinity(trainer)
  
file_path: zoo/src/callbacks/gpu_affinity.py
imports: import torch
  from pytorch_lightning import Callback, Trainer, LightningModule
  import logging
label_desc: Use image node_id 1 for calling the GpuAffinity obj's underlying member method code with example usage: obj.setup(trainer, pl_module, stage) without return types