code: def _choose_gpu_accelerator_backend() -> str:
      if MPSAccelerator.is_available():
          return "mps"
      if CUDAAccelerator.is_available():
          return "cuda"
      raise MisconfigurationException("No supported gpu backend found!")
  
imports: import logging
  import os
  from collections import Counter
  from typing import Dict, List, Literal, Optional, Union
  import torch
  from lightning.fabric.connector import _PRECISION_INPUT, _PRECISION_INPUT_STR, _convert_precision_to_unified_args
  from lightning.fabric.plugins.environments import ClusterEnvironment, LightningEnvironment, LSFEnvironment, MPIEnvironment, SLURMEnvironment, TorchElasticEnvironment
  from lightning.fabric.utilities.device_parser import _determine_root_gpu_device
  from lightning.fabric.utilities.imports import _IS_INTERACTIVE
  from lightning.pytorch.accelerators import AcceleratorRegistry
  from lightning.pytorch.accelerators.accelerator import Accelerator
  from lightning.pytorch.accelerators.cuda import CUDAAccelerator
  from lightning.pytorch.accelerators.mps import MPSAccelerator
  from lightning.pytorch.accelerators.xla import XLAAccelerator
  from lightning.pytorch.plugins import _PLUGIN_INPUT, CheckpointIO, DeepSpeedPrecision, DoublePrecision, FSDPPrecision, HalfPrecision, MixedPrecision, Precision, TransformerEnginePrecision, XLAPrecision
  from lightning.pytorch.plugins.layer_sync import LayerSync, TorchSyncBatchNorm
  from lightning.pytorch.strategies import DDPStrategy, DeepSpeedStrategy, FSDPStrategy, ParallelStrategy, SingleDeviceStrategy, SingleDeviceXLAStrategy, Strategy, StrategyRegistry, XLAStrategy
  from lightning.pytorch.strategies.ddp import _DDP_FORK_ALIASES
  from lightning.pytorch.utilities.exceptions import MisconfigurationException
  from lightning.pytorch.utilities.imports import _LIGHTNING_BAGUA_AVAILABLE, _LIGHTNING_COLOSSALAI_AVAILABLE, _graphcore_available_and_importable, _habana_available_and_importable
  from lightning.pytorch.utilities.rank_zero import rank_zero_info, rank_zero_warn
label_desc: Use image node_id 5 for calling the _AcceleratorConnector obj's underlying member method code with example usage: obj._choose_gpu_accelerator_backend() and returns: str, str