code: def get_backend(self, entrypoint_file: str) -> "Backend":
      if self == BackendType.MULTIPROCESSING:
          if APP_SERVER_IN_CLOUD:
              return CloudMultiProcessingBackend(entrypoint_file)
          return MultiProcessingBackend(entrypoint_file)
      if self == BackendType.DOCKER:
          return DockerBackend(entrypoint_file)
      if self == BackendType.CLOUD:
          return CloudBackend(entrypoint_file)
      raise ValueError("Unknown client type")
  
file_path: pytorch-lightning/src/lightning/app/runners/backends/__init__.py
imports: from enum import Enum
  from lightning.app.core.constants import APP_SERVER_IN_CLOUD
  from lightning.app.runners.backends.backend import Backend
  from lightning.app.runners.backends.cloud import CloudBackend
  from lightning.app.runners.backends.docker import DockerBackend
  from lightning.app.runners.backends.mp_process import CloudMultiProcessingBackend, MultiProcessingBackend
label_desc: Use image node_id 1 for calling the BackendType obj's underlying member method code with example usage: obj.get_backend(entrypoint_file) and returns: MultiProcessingBackend, DockerBackend, CloudBackend, CloudMultiProcessingBackend