prefix :       <http://example.org/>
prefix xsd:    <http://www.w3.org/2001/XMLSchema#>

:ok_b :p "A", "B" .             # Should pass as B
:ko_b :p "A", "B"; :q "C" .     # Should fail as B
:ok_c :p "C" .             # Should pass as C
:ko_c1 :p "A", "C" .
:ko_c2 :p "C"; :q "?" .
