PREFIX  jfn:  <java:com.hp.hpl.jena.query.function.library.>
PREFIX  jx:   <java:com.hp.hpl.jena.query.extension.library.>
PREFIX :      <http://example/>

SELECT ?x ?p ?v ?AGG1
{
    ?x ?p ?v .
#    FILTER jfn:print()
    EXT jx:group(?v)

}
## ORDER BY ?v ?p