<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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)