code: def is_name_expired( self, name, block_number ):
          
          cur = self.db.cursor()
          return namedb_get_name( cur, name, block_number ) is None
docs: Given a name and block number, determine if it is expired at that block.
          * names in revealed but not ready namespaces are never expired, unless the namespace itself is expired;
          * names in ready namespaces expire once max(ready_block, renew_block) + lifetime blocks passes
  
          Return True if so
          Return False if not, or if the name doesn't exist