def forward(self, x, timesteps, **kwargs):
    (_, _, new_height, new_width) = x.shape
    upsampled = F.interpolate(kwargs.pop('low_res'), (new_height, new_width), mode='bilinear')
    x = th.cat([x, upsampled], dim=1)
    return super().forward(x, timesteps, **kwargs)
def forward(self, x, timesteps, **kwargs):
    (_, _, new_height, new_width) = x.shape
    upsampled = F.interpolate(kwargs.pop('low_res'), (new_height, new_width), mode='bilinear')
    x = th.cat([x, upsampled], dim=1)
    return super().forward(x, timesteps, **kwargs)