'Apply the backward pass transformation to the input data.
Arguments:
error (Tensor): deltas back propagated from the adjacent higher layer
Returns:
Tensor: deltas to propagate to the adjacent lower layer'

def bprop(self, error):

    self.be.bprop_transform(self.nglayer, self.transform, self.outputs, error, self.deltas, (type(self.transform) == Rectlin))
    return self.deltas
