Generate and return the sequence of states a namespace record was in
        at a particular block number.

        Includes expired namespaces by default.

def get_namespace_at( self, namespace_id, block_number ):
        """
        Generate and return the sequence of states a namespace record was in
        at a particular block number.

        Includes expired namespaces by default.
        """
        cur = self.db.cursor() 
        return namedb_get_namespace_at(cur, namespace_id, block_number, include_expired=True)