Tuple of downsample block types.
mid_block_type (`str`, *optional*, defaults to `"UNetMidBlock2D"`):
Block type for middle of UNet, it can be either `UNetMidBlock2D` or `None`.
up_block_types (`Tuple[str]`, *optional*, defaults to `("AttnUpBlock2D", "AttnUpBlock2D", "AttnUpBlock2D", "UpBlock2D")`):
Tuple of upsample block types.
block_out_channels (`Tuple[int]`, *optional*, defaults to `(224, 448, 672, 896)`):
Tuple of block output channels.