rg.de/people/ronneber/u-net.  UNet2DModel  class diffusers.UNet2DModel  < source > ( sample_size: Union = None in_channels: int = 3 out_channels: int = 3 center_input_sample: bool = False time_embedding_type: str = 'positional' freq_shift: int = 0 flip_sin_to_cos: bool = True down_block_types: Tuple = ('DownBlock2D', 'AttnDownBlock2D', 'AttnDownBlock2D', 'AttnDownBlock2D') up_block_types: Tuple = ('AttnUpBlock2D', 'AttnUpBlock2D', 'AttnUpBlock2