NotImplementedError

跑通加了SE注意力机制的YOLOv5时，出现以下情况

``` Traceback (most recent call last):
  File "E:\object detection\YOLOv5\yolov5-5.0\train.py", line 547, in 
    train(hyp, opt, device, tb_writer)
  File "E:\object detection\YOLOv5\yolov5-5.0\train.py", line 90, in train
    model = Model(opt.cfg or ckpt['model'].yaml, ch=3, nc=nc, anchors=hyp.get('anchors')).to(device)  # create
  File "E:\object detection\YOLOv5\yolov5-5.0\models\yolo.py", line 123, in __init__
    m.stride = torch.tensor([s / x.shape[-2] for x in self.forward(torch.zeros(1, ch, s, s))])  # forward
  File "E:\object detection\YOLOv5\yolov5-5.0\models\yolo.py", line 156, in forward
    return self.forward_once(x, profile)  # single-scale inference, train
  File "E:\object detection\YOLOv5\yolov5-5.0\models\yolo.py", line 182, in forward_once
    x = m(x)  # run 正向推理
  File "D:\anaconda\envs\pytorch\lib\site-packages\torch\nn\modules\module.py", line 1110, in _call_impl
    return forward_call(*input, **kwargs)
  File "D:\anaconda\envs\pytorch\lib\site-packages\torch\nn\modules\module.py", line 201, in _forward_unimplemented
    raise NotImplementedError
NotImplementedError

但是之前没有加SE模块时，代码也能正常跑通