code: def barrier() -> None:
      """
      Add a synchronization point across all processes when using distributed.
      If torch.distributed is initialized, this function will invoke a barrier across the global process group.
      For more granular process group wrapping, please refer to :class:`~torchtnt.utils.PGWrapper`.
      """
      if not (dist.is_available() and dist.is_initialized()):
          return
      backend = dist.get_backend()
      if backend == dist.Backend.NCCL:
          dist.barrier(device_ids=[torch.cuda.current_device()])
      else:
          dist.barrier()
  
imports: import os
  import tempfile
  from functools import wraps
  from typing import Any, Callable, cast, List, Optional, TypeVar, Union
  import torch
  import torch.distributed
  import torch.nn.functional
  from torch import Tensor
  from torch.distributed.elastic.utils.distributed import get_free_port
  from typing_extensions import Literal
label_desc: Use image node_id 5 for calling a global function with example usage: barrier() without return types