1.5.24. How can I dump arbitrary query result as N-Triples?

Assume the following arbitrary query:

SPARQL define output:format "NT"
CONSTRUCT { ?s a ?t }
FROM virtrdf:
WHERE { ?s a ?t };

For iteration over result-set of an arbitrary query, use exec_next() in a loop that begins with exec() with cursor output variable as an argument and ends with exec_close() after it is out of data.