In my forward function, I run `nn.MSELoss()`

forwards, but I need to run it (or something similar) backwards, inside my backwards function.

For example:

```
class InputLoss(nn.Module):
def __init__(self, strength, normalize):
self.loss = self.strength
self.target = torch.Tensor()
self.crit = nn.MSELoss()
def forward(self, input):
self.loss = self.crit(input, self.target) * strength # Forward Crit
def backward(self, input, gradOutput):
self.gradInput = self.crit.backward(input, self.target) * strength # Backward Crit
```

How would I got about doing this?