@prefix sp: <http://spinrdf.org/sp#>.
@prefix spin: <http://spinrdf.org/spin#>.
@prefix ex: <ex:>.

[ a sp:Select ;
	sp:text """
PREFIX ex: <ex:>

SELECT *
WHERE {
    OPTIONAL { ?this ex:firstName ?value }
}
""";
    sp:resultVariables  (
    	spin:_this 
    	_:value );
	sp:where (
    [ a       sp:Optional ;
      sp:elements ([ sp:subject spin:_this ;
                     sp:predicate ex:firstName ;
                     sp:object _:value
                   ])
    ]);
].

_:value sp:varName "value" .
