code: def zero_grad(model: torch.nn.Module) -> None:
      if torch_version() >= (1, 7, 0):
          model.zero_grad(set_to_none=True)
      else:
          for p in model.parameters():
              p.grad = None
  
imports: import contextlib
  from types import SimpleNamespace
  from typing import Any, Dict
  import torch
  from classy_vision.generic.distributed_util import all_reduce_mean
  from classy_vision.tasks import ClassyTask
  from classy_vision.tasks.classification_task import AmpType
  from vissl.hooks import SSLClassyHookFunctions
  from vissl.trainer.train_steps import register_train_step
  from vissl.utils.activation_checkpointing import manual_gradient_all_reduce, manual_sync_params
  from vissl.utils.fsdp_utils import is_fsdp_model
  from vissl.utils.misc import is_apex_available, torch_version
  from vissl.utils.perf_stats import PerfTimer
  from vissl.utils.profiler import record_function
label_desc: Use image node_id 1 for calling a global function with example usage: zero_grad(model) without return types