              The backend configuration in use by Faceswap
          """
          # Check if environment variable is set, if so use that
          if "FACESWAP_BACKEND" in os.environ:
              fs_backend = os.environ["FACESWAP_BACKEND"].lower()
              print(f"Setting Faceswap backend from environment variable to {fs_backend.upper()}")
              return fs_backend
          # Intercept for sphinx docs build
          if sys.argv[0].endswith("sphinx-build"):
              return "nvidia"
 
</s> remove         return fs_backend.lower()
 </s> add         return fs_backend </s> remove         fs_backend = config.get("backend", None)
        if fs_backend is None or fs_backend.lower() not in self._backends.values():
 </s> add         fs_backend = config.get("backend", "").lower()
        if not fs_backend or fs_backend not in self._backends.values(): </s> remove     def _configure_backend(self):
 </s> add     def _configure_backend(self) -> ValidBackends: </s> remove _FS_BACKEND = _Backend().backend
 </s> add _FS_BACKEND: ValidBackends = _Backend().backend </s> remove def get_backend():
 </s> add def get_backend() -> ValidBackends:
            fs_backend = cast(ValidBackends, os.environ["FACESWAP_BACKEND"].lower())
            assert fs_backend in get_args(ValidBackends), (
                f"Faceswap backend must be one of {get_args(ValidBackends)}")
              The backend configuration in use by Faceswap
          """
          # Check if environment variable is set, if so use that
          if "FACESWAP_BACKEND" in os.environ:
            fs_backend = cast(ValidBackends, os.environ["FACESWAP_BACKEND"].lower())
            assert fs_backend in get_args(ValidBackends), (
                f"Faceswap backend must be one of {get_args(ValidBackends)}")
              print(f"Setting Faceswap backend from environment variable to {fs_backend.upper()}")
              return fs_backend
          # Intercept for sphinx docs build
          if sys.argv[0].endswith("sphinx-build"):
              return "nvidia"
keep keep keep keep replace keep keep keep keep keep
 lib.Utils - add DPI detector 
lib/utils.py