code: def forward(ctx, op, group, tensor):
      ctx.group = group
      ctx.op = op
      tensor = tensor.clone()
      dist.all_reduce(tensor, op=op, group=group)
      return tensor
  
imports: import torch
  import torch.distributed
  from torch.autograd import Function
  from torch.distributed import group, ReduceOp
label_desc: Use image node_id 1 for calling the _AllReduce obj's underlying member method code with example usage: obj.forward(ctx, op, group, tensor) and returns: tensor