out_block_type (`str`, *optional*, defaults to `None`): Optional output processing block of UNet.
act_fn (`str`, *optional*, defaults to `None`): Optional activation function in UNet blocks.
norm_num_groups (`int`, *optional*, defaults to 8): The number of groups for normalization.
layers_per_block (`int`, *optional*, defaults to 1): The number of layers per block.
downsample_each_block (`int`, *optional*, defaults to `False`):
Experimental feature for using a UNet without upsampling.