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