stage might be referenced before asignment

[814696032]

detectron2-ResNeSt/detectron2/modeling/backbone/fpn.py

Line 96 in 54ec876

 for s in range(stage, stage + self.top_block.num_levels): 

I want to apply the backbone in my custom net , but there seems a problem in fpn.py in line 96
The "stage" is used before reference, How can I solve this ?
Thanks for your reply!