docstr: Attach the backend to all flows and its children.
docstr_tok: ["Attach","the","backend","to","all","flows","and","its","children","."]
code: def _attach_backend(
      flow: "LightningFlow", backend: "Backend"
  ) -> None:
      """Attach the backend to all flows and its children."""
      flow._backend = backend
  
      for name in flow._structures:
          getattr(flow, name)._backend = backend
  
      for child_flow in flow.flows.values():
          child_flow._backend = backend
          for name in child_flow._structures:
              getattr(child_flow, name)._backend = backend
  
      app = _LightningAppRef().get_current()
  
      for child_work in flow.works():
          child_work._backend = backend
          backend._wrap_run_method(app, child_work)
  
imports: import inspect
  import warnings
  from copy import deepcopy
  from datetime import datetime
  from types import FrameType
  from typing import TYPE_CHECKING, Any, Dict, Generator, Iterable, List, Optional, Tuple, Union, cast
  from deepdiff import DeepHash
  from lightning.app.core.work import LightningWork
  from lightning.app.frontend import Frontend
  from lightning.app.storage.drive import Drive, _maybe_create_drive
  from lightning.app.storage.path import Path
  from lightning.app.utilities.app_helpers import _is_json_serializable, _LightningAppRef, _set_child_name, is_overridden
  from lightning.app.utilities.component import _sanitize_state
  from lightning.app.utilities.exceptions import ExitAppException, LightningFlowException
  from lightning.app.utilities.introspection import _is_init_context, _is_run_context
  from lightning.app.utilities.packaging.cloud_compute import CloudCompute, _maybe_create_cloud_compute
label_desc: Use image node_id 4 for calling the LightningFlow obj's underlying member method code with example usage: obj._attach_backend(flow, backend) without return types