def get_errors(self, inputs, targets_mask):
        targets, mask = targets_mask
        self.deltas[:] = self.costfunc.bprop(inputs, targets) * mask
        return self.deltas
Compute the derivative of the cost function
dataset/ETHPy150Open NervanaSystems/neon/neon/layers/layer.py/GeneralizedCostMask.get_errors