# FAQ

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<font size=3>**Q: FastGradientSignMethod未指定loss_fn时报错`Function construct_wrapper, The number of parameters of this function is 9, but the number of provided arguments is 10.`怎么办？**</font>

A: class mindarmour.adv_robustness.attacks.FastGradientSignMethod(network, eps=0.07, alpha=None, bounds=(0.0,1.0), is_targeted=False, loss_fn=None)中，如果传入的network不是WithLossCell的形式，需要指定Loss_fn，由执行过程自动执行WithLossCell操作，否则会出现输入参数数量和函数所需参数数量不一致的错误。