from pytorch_lightning.accelerators.cpu_backend import CPUBackend
from pytorch_lightning.accelerators.ddp2_backend import DDP2Backend
from pytorch_lightning.accelerators.ddp_backend import DDPBackend
from pytorch_lightning.accelerators.ddp_spawn_backend import DDPSpawnBackend
from pytorch_lightning.accelerators.dp_backend import DataParallelBackend
from pytorch_lightning.accelerators.gpu_backend import GPUBackend
from pytorch_lightning.accelerators.tpu_backend import TPUBackend