code: def get_backend_instance(self, backend: BackendDefinitionType) -> BaseBackend:
          
          if backend is NOT_SET:
              backend = self.get_setting("backend", "arca.CurrentEnvironmentBackend")
  
          if isinstance(backend, str):
              backend = load_class(backend)
  
          if callable(backend):
              backend = backend()
  
          if not issubclass(type(backend), BaseBackend):
              raise ArcaMisconfigured(f"{type(backend)} is not an subclass of BaseBackend")
  
          return backend
docs: Returns a backend instance, either from the argument or from the settings.
  
          :raise ArcaMisconfigured: If the instance is not a subclass of :class:`BaseBackend`