def forward(self, x: Tensor) -> Tensor:
        """Return double-swish activation function which is an approximation to Swish(Swish(x)),
        that we approximate closely with x * sigmoid(x-1).
        """
        if torch.jit.is_scripting() or torch.jit.is_tracing():
            return x * torch.sigmoid(x - 1.0)
        return DoubleSwishFunction.apply(x)
Return double-swish activation function which is an approximation to Swish(Swish(x)),
        that we approximate closely with x * sigmoid(x-1).
        
parrots/t2s_utils.py