I want to define a custom layer, the layer has a parameter weight, the layer contain several  Conv2d operation, and the Conv2d’s weight is calculated based on the weight I defined before, the custom layer weight’s grad is based on the Conv2d weight’s grad, now I have problem to upgrade the custom layer’s weight. As the custom layer weight is not included in the compute graph, when I want to compute it’s grad it shows  the type of weight.grad is <type ‘NoneType’>, how can I update the parameter’s grad not included in the computation graph and use the solver to update the parameter.