Hey, everyone!

Is there any way to accumulate the gradients with the abs()? I want to do some analysis using the absolute value of the gradients.

The following is an example:

```
a1_grad = torch.autograd.grad(pred[0], input, create_graph=False, retain_graph=True)[0]
a2_grad = torch.autograd.grad(pred[10], input, create_graph=False, retain_graph=True)[0]
a12_grad = torch.autograd.grad(pred[0]+pred[10], input, create_graph=False, retain_graph=True)[0]
```

My goal is to let **a12_grad == ( a1_grad.abs() + a2_grad.abs() )**

Thanks in advance!