The debugger ends in the module “scatter_gather.py” on line 13 in the nested function “def scatter_map(obj)”: return Scatter.apply(target_gpus, None, dim, obj). At this point, obj is “tensor(533958, device=‘cuda:0’)”. It I step up one level, the code is on line 15 in the same nested function “def scatter_map(obj)”: return list(zip(*map(scatter_map, obj))). Here “obj” is (‘image_id’, tensor(533958, device=‘cuda:0’)). “image_id” is a field in the target dictionary, which seems to indicate that the code is trying to scatter the fields in the target dictionary