def default(self, block, name):
        """
        Ask the kvs for the default (default implementation which other classes may override).

        :param block: block containing field to default
        :type block: :class:`~xblock.core.XBlock`
        :param name: name of the field to default
        """
        return self._kvs.default(self._key(block, name))
Ask the kvs for the default (default implementation which other classes may override).

        :param block: block containing field to default
        :type block: :class:`~xblock.core.XBlock`
        :param name: name of the field to default