code: def cat_all_gather(tensors, local=False):
      """Performs the concatenated all_reduce operation on the provided tensors."""
      if local:
          gather_sz = get_local_size()
      else:
          gather_sz = torch.distributed.get_world_size()
      tensors_gather = [
          torch.ones_like(tensors) for _ in range(gather_sz)
      ]
      torch.distributed.all_gather(
          tensors_gather,
          tensors,
          async_op=False,
          group=_LOCAL_PROCESS_GROUP if local else None,
      )
      output = torch.cat(tensors_gather, dim=0)
      return output
  
file_path: pytorchvideo/pytorchvideo/layers/distributed.py
imports: import torch
  import torch.distributed
  from torch._C._distributed_c10d import ProcessGroup
  from torch.autograd.function import Function
label_desc: Use image node_id 2 for calling a global function with example usage: cat_all_gather(tensors, local) and returns: output