class_docstr: The Connector parses several Fabric arguments and instantiates the Strategy including its owned components.
  
      A. accelerator flag could be:
          1. accelerator class
          2. accelerator str
          3. accelerator auto
  
      B. strategy flag could be:
          1. strategy class
          2. strategy str registered with STRATEGY_REGISTRY
          3. strategy str in _strategy_type enum which listed in each strategy as
             backend (registed these too, and _strategy_type could be deprecated)
  
      C. plugins flag could be:
          1. precision class (should be removed, and precision flag should allow user pass classes)
          2. checkpoint_io class
          3. cluster_environment class
  
  priorities which to take when:
      A. Class > str
      B. Strategy > Accelerator/precision/plugins
docstr: This method checks:
  
  1. strategy: whether the strategy name is valid, and sets the internal flags if it is.
  2. accelerator: if the value of the accelerator argument is a type of accelerator (instance or string),
      set self._accelerator_flag accordingly.
  3. precision: The final value of the precision flag may be determined either by the precision argument or
      by a plugin instance.
  4. plugins: The list of plugins may contain a Precision plugin, CheckpointIO, ClusterEnvironment and others.
      Additionally, other flags such as `precision` can populate the list with the
      corresponding plugin instances.
docstr_tok: ["This","method","checks",":","1.","strategy",":","whether","the","strategy","name","is","valid",",","and","sets","the","internal","flags","if","it","is",".","2.","accelerator",":","if","the","value","of","the","accelerator","argument","is","a","type","of","accelerator","(","instance","or","string",")",",","set","self._accelerator_flag","accordingly",".","3.","precision",":","The","final","value","of","the","precision","flag","may","be","determined","either","by","the","precision","argument","or","by","a","plugin","instance",".","4.","plugins",":","The","list","of","plugins","may","contain","a","Precision","plugin",",","CheckpointIO",",","ClusterEnvironment","and","others",".","Additionally",",","other","flags","such","as","`","precision","`","can","populate","the","list","with","the","corresponding","plugin","instances","."]
code: def _check_config_and_set_final_flags(
      self,
      strategy: Union[str, Strategy],
      accelerator: Union[str, Accelerator],
      precision: Optional[_PRECISION_INPUT],
      plugins: Optional[Union[_PLUGIN_INPUT, List[_PLUGIN_INPUT]]],
  ) -> None:
      """This method checks:
  
      1. strategy: whether the strategy name is valid, and sets the internal flags if it is.
      2. accelerator: if the value of the accelerator argument is a type of accelerator (instance or string),
          set self._accelerator_flag accordingly.
      3. precision: The final value of the precision flag may be determined either by the precision argument or
          by a plugin instance.
      4. plugins: The list of plugins may contain a Precision plugin, CheckpointIO, ClusterEnvironment and others.
          Additionally, other flags such as `precision` can populate the list with the
          corresponding plugin instances.
  
      """
      if plugins is not None:
          plugins = (
              [plugins] if not isinstance(plugins, list) else plugins
          )
  
      if isinstance(strategy, str):
          strategy = strategy.lower()
  
      self._strategy_flag = strategy
  
      if (
          strategy != "auto"
          and strategy not in self._registered_strategies
          and not isinstance(strategy, Strategy)
      ):
          raise ValueError(
              f"You selected an invalid strategy name: `strategy={strategy!r}`."
              " It must be either a string or an instance of `lightning.fabric.strategies.Strategy`."
              " Example choices: auto, ddp, ddp_spawn, deepspeed, dp, ..."
              " Find a complete list of options in our documentation at https://lightning.ai"
          )
  
      if (
          accelerator not in self._registered_accelerators
          and accelerator not in ("auto", "gpu")
          and not isinstance(accelerator, Accelerator)
      ):
          raise ValueError(
              f"You selected an invalid accelerator name: `accelerator={accelerator!r}`."
              f" Available names are: auto, {', '.join(self._registered_accelerators)}."
          )
  
      # MPS accelerator is incompatible with DDP family of strategies. It supports single-device operation only.
      is_ddp_str = isinstance(strategy, str) and "ddp" in strategy
      is_dp_str = isinstance(strategy, str) and "dp" in strategy
      is_deepspeed_str = (
          isinstance(strategy, str) and "deepspeed" in strategy
      )
      is_parallel_strategy = (
          isinstance(strategy, ParallelStrategy)
          or is_ddp_str
          or is_dp_str
          or is_deepspeed_str
      )
      is_mps_accelerator = MPSAccelerator.is_available() and (
          accelerator in ("mps", "auto", "gpu", None)
          or isinstance(accelerator, MPSAccelerator)
      )
      if is_mps_accelerator and is_parallel_strategy:
          raise ValueError(
              f"You set `strategy={strategy}` but strategies from the DDP family are not supported on the"
              f" MPS accelerator. Either explicitly set `accelerator='cpu'` or change the strategy."
          )
  
      self._accelerator_flag = accelerator
  
      precision_input = _convert_precision_to_unified_args(precision)
  
      if plugins:
          plugins_flags_types: Dict[str, int] = Counter()
          for plugin in plugins:
              if isinstance(plugin, Precision):
                  self._precision_instance = plugin
                  plugins_flags_types[Precision.__name__] += 1
              elif isinstance(plugin, CheckpointIO):
                  self.checkpoint_io = plugin
                  plugins_flags_types[CheckpointIO.__name__] += 1
              elif isinstance(plugin, ClusterEnvironment):
                  self._cluster_environment_flag = plugin
                  plugins_flags_types[ClusterEnvironment.__name__] += 1
              else:
                  raise TypeError(
                      f"Found invalid type for plugin {plugin}. Expected one of: Precision, "
                      "CheckpointIO, ClusterEnviroment."
                  )
  
          duplicated_plugin_key = [
              k for k, v in plugins_flags_types.items() if v > 1
          ]
          if duplicated_plugin_key:
              raise ValueError(
                  f"Received multiple values for {', '.join(duplicated_plugin_key)} flags in `plugins`."
                  " Expected one value for each type at most."
              )
  
          if (
              plugins_flags_types.get(Precision.__name__)
              and precision_input is not None
          ):
              raise ValueError(
                  f"Received both `precision={precision_input}` and `plugins={self._precision_instance}`."
                  f" Choose one."
              )
  
      self._precision_input = (
          "32-true" if precision_input is None else precision_input
      )
  
      # handle the case when the user passes in a strategy instance which has an accelerator, precision,
      # checkpoint io or cluster env set up
      # TODO: improve the error messages below
      if isinstance(self._strategy_flag, Strategy):
          if self._strategy_flag._accelerator:
              if self._accelerator_flag != "auto":
                  raise ValueError(
                      "accelerator set through both strategy class and accelerator flag, choose one"
                  )
              self._accelerator_flag = self._strategy_flag._accelerator
          if self._strategy_flag._precision:
              # [RFC] handle precision plugin set up conflict?
              if self._precision_instance:
                  raise ValueError(
                      "precision set through both strategy class and plugins, choose one"
                  )
              self._precision_instance = self._strategy_flag._precision
          if self._strategy_flag._checkpoint_io:
              if self.checkpoint_io:
                  raise ValueError(
                      "checkpoint_io set through both strategy class and plugins, choose one"
                  )
              self.checkpoint_io = self._strategy_flag._checkpoint_io
          if getattr(self._strategy_flag, "cluster_environment", None):
              if self._cluster_environment_flag:
                  raise ValueError(
                      "cluster_environment set through both strategy class and plugins, choose one"
                  )
              self._cluster_environment_flag = getattr(
                  self._strategy_flag, "cluster_environment"
              )
  
          if (
              hasattr(self._strategy_flag, "parallel_devices")
              and self._strategy_flag.parallel_devices
          ):
              if self._strategy_flag.parallel_devices[0].type == "cpu":
                  if (
                      self._accelerator_flag
                      and self._accelerator_flag not in ("auto", "cpu")
                  ):
                      raise ValueError(
                          f"CPU parallel_devices set through {self._strategy_flag.__class__.__name__} class,"
                          f" but accelerator set to {self._accelerator_flag}, please choose one device type"
                      )
                  self._accelerator_flag = "cpu"
              if self._strategy_flag.parallel_devices[0].type == "cuda":
                  if (
                      self._accelerator_flag
                      and self._accelerator_flag
                      not in ("auto", "cuda", "gpu")
                  ):
                      raise ValueError(
                          f"GPU parallel_devices set through {self._strategy_flag.__class__.__name__} class,"
                          f" but accelerator set to {self._accelerator_flag}, please choose one device type"
                      )
                  self._accelerator_flag = "cuda"
              self._parallel_devices = (
                  self._strategy_flag.parallel_devices
              )
  
imports: import os
  from collections import Counter
  from typing import Any, Dict, List, Optional, Union, cast
  import torch
  from typing_extensions import get_args
  from lightning.fabric.accelerators import ACCELERATOR_REGISTRY
  from lightning.fabric.accelerators.accelerator import Accelerator
  from lightning.fabric.accelerators.cuda import CUDAAccelerator
  from lightning.fabric.accelerators.mps import MPSAccelerator
  from lightning.fabric.accelerators.xla import XLAAccelerator
  from lightning.fabric.plugins import CheckpointIO, DeepSpeedPrecision, HalfPrecision, MixedPrecision, Precision, TransformerEnginePrecision, XLAPrecision
  from lightning.fabric.plugins.environments import ClusterEnvironment, LightningEnvironment, LSFEnvironment, MPIEnvironment, SLURMEnvironment, TorchElasticEnvironment
  from lightning.fabric.plugins.precision.double import DoublePrecision
  from lightning.fabric.plugins.precision.fsdp import FSDPPrecision
  from lightning.fabric.plugins.precision.precision import _PRECISION_INPUT, _PRECISION_INPUT_INT, _PRECISION_INPUT_STR, _PRECISION_INPUT_STR_ALIAS, _PRECISION_INPUT_STR_ALIAS_CONVERSION
  from lightning.fabric.strategies import STRATEGY_REGISTRY, DeepSpeedStrategy, ParallelStrategy, SingleDeviceStrategy, SingleDeviceXLAStrategy, Strategy, XLAFSDPStrategy, XLAStrategy
  from lightning.fabric.strategies.ddp import _DDP_FORK_ALIASES
  from lightning.fabric.strategies.fsdp import _FSDP_ALIASES, FSDPStrategy
  from lightning.fabric.utilities import rank_zero_info, rank_zero_warn
  from lightning.fabric.utilities.device_parser import _determine_root_gpu_device
  from lightning.fabric.utilities.imports import _IS_INTERACTIVE
label_desc: Use image node_id 2 for calling the _Connector obj's underlying member method code with example usage: obj._check_config_and_set_final_flags(strategy, accelerator, precision, plugins) without return types