Create an instance of this resource definition.

        Only one instance may exist at any given time.

def create(self, **kwargs):
        """
        Create an instance of this resource definition.

        Only one instance may exist at any given time.
        """
        if self.created:
            raise RuntimeError(
                '{} already created.'.format(self.__model_type__.__name__))

        kwargs = self.merge_kwargs(self._create_kwargs, kwargs)

        self._inner = self.helper.create(
            self.name, *self._create_args, **kwargs)