ss_embed_type equal to None.    A 2D UNet model that takes a noisy sample and a timestep and returns a sample shaped output. This model inherits from ModelMixin. Check the superclass documentation for it’s generic methods implemented
for all models (such as downloading or saving).  forward  < source > ( sample: FloatTensor timestep: Union class_labels: Optional = None return_dict: bool = True  ) → ~models.unet_2d.UNet2DOutput or tuple  Paramete