def set_contains(self, key, value):
        """
        Determine if an item exists in a set
        :param key: The document ID of the set
        :param value: The value to check for
        :return: True if `value` exists in the set
        :raise: :cb_exc:`NotFoundError` if the document does not exist
        """
        rv = self.get(key)
        return value in rv.value
Determine if an item exists in a set
        :param key: The document ID of the set
        :param value: The value to check for
        :return: True if `value` exists in the set
        :raise: :cb_exc:`NotFoundError` if the document does not exist