How to use the lpips.util.util.tensor2np function in lpips

def forward(self, in0, in1):
        assert(in0.size()[0]==1) # currently only supports batchSize 1

        if(self.colorspace=='RGB'):
            value = util.dssim(1.*util.tensor2im(in0.data), 1.*util.tensor2im(in1.data), range=255.).astype('float')
        elif(self.colorspace=='Lab'):
            value = util.dssim(util.tensor2np(util.tensor2tensorlab(in0.data,to_norm=False)),
                util.tensor2np(util.tensor2tensorlab(in1.data,to_norm=False)), range=100.).astype('float')
        ret_var = Variable( torch.Tensor((value,) ) )
        if(self.use_gpu):
            ret_var = ret_var.cuda()
        return ret_var