docs: def validate_args(self):
          """
          Validates arguments.
          """
          from ..mixins import ModelMixin
  
          for arg in ("instance", "decider", "identifier", "fields", "default_language"):
              if getattr(self, arg) is None:
                  raise AttributeError("%s must not be None" % arg)
  
          if not isinstance(self.instance, (ModelMixin,)):
              raise ImproperlyConfigured('"instance" argument must be a Linguist model')
  
          if not issubclass(self.decider, (models.Model,)):
              raise ImproperlyConfigured(
                  '"decider" argument must be a valid Django model'
              )