code: def create_ddp_model(model, *, fp16_compression=False, **kwargs):
      """
      Create a DistributedDataParallel model if there are >1 processes.
  
      Args:
          model: a torch.nn.Module
          fp16_compression: add fp16 compression hooks to the ddp object.
              See more at https://pytorch.org/docs/stable/ddp_comm_hooks.html#torch.distributed.algorithms.ddp_comm_hooks.default_hooks.fp16_compress_hook
          kwargs: other arguments of :module:`torch.nn.parallel.DistributedDataParallel`.
      """  # noqa
      if comm.get_world_size() == 1:
          return model
      if "device_ids" not in kwargs:
          kwargs["device_ids"] = [comm.get_local_rank()]
      ddp = DistributedDataParallel(model, **kwargs)
      if fp16_compression:
          from torch.distributed.algorithms.ddp_comm_hooks import (
              default as comm_hooks,
          )
  
          ddp.register_comm_hook(
              state=None, hook=comm_hooks.fp16_compress_hook
          )
      return ddp
  
imports: import argparse
  import logging
  import os
  import sys
  import weakref
  from collections import OrderedDict
  from typing import Optional
  import torch
  from fvcore.nn.precise_bn import get_bn_modules
  from omegaconf import OmegaConf
  from torch.nn.parallel import DistributedDataParallel
  import detectron2.data.transforms
  from detectron2.checkpoint import DetectionCheckpointer
  from detectron2.config import CfgNode, LazyConfig
  from detectron2.data import MetadataCatalog, build_detection_test_loader, build_detection_train_loader
  from detectron2.evaluation import DatasetEvaluator, inference_on_dataset, print_csv_format, verify_results
  from detectron2.modeling import build_model
  from detectron2.solver import build_lr_scheduler, build_optimizer
  from detectron2.utils import comm
  from detectron2.utils.collect_env import collect_env_info
  from detectron2.utils.env import seed_all_rng
  from detectron2.utils.events import CommonMetricPrinter, JSONWriter, TensorboardXWriter
  from detectron2.utils.file_io import PathManager
  from detectron2.utils.logger import setup_logger
  from .None import hooks
  from .train_loop import AMPTrainer, SimpleTrainer, TrainerBase
label_desc: Use image node_id 1 for calling a global function with example usage: create_ddp_model(model) and returns: ddp, model