@prefix : <http://www.w3.org/2004/ql#>.
@prefix q: <http://www.w3.org/2004/ql#>.
@prefix ex: <http://www.example.com/foo#>.
@prefix math: <http://www.w3.org/2000/10/swap/math#>.
@keywords a.

[] select { result is (?x ?y) };
   where  { ?x a ex:Librarian;  ex:hairColor ?y }.