Fetch a resource from the API.
        Either the `id` or the `slug` has to be present.

        :param id: The ID of the resource
        :param slug: The slug of the resource
        :param kwargs: Parameters for the request
            (see from and below https://api.ghost.org/docs/limit)
        :return: The item returned by the API
            wrapped as a `Model` object

def get(self, id=None, slug=None, **kwargs):
        """
        Fetch a resource from the API.
        Either the `id` or the `slug` has to be present.

        :param id: The ID of the resource
        :param slug: The slug of the resource
        :param kwargs: Parameters for the request
            (see from and below https://api.ghost.org/docs/limit)
        :return: The item returned by the API
            wrapped as a `Model` object
        """

        if id:
            items = self.ghost.execute_get('%s/%s/' % (self._type_name, id), **kwargs)

        elif slug:
            items = self.ghost.execute_get('%s/slug/%s/' % (self._type_name, slug), **kwargs)

        else:
            raise GhostException(
                500, 'Either the ID or the Slug of the resource needs to be specified'
            )

        return self._model_type(items[self._type_name][0])