lights_g(Delay) :-
          sleep(Delay),
          format('~ttraffic lights, case 1~n'),
          setSFColor(id, 'RLight', 1.0, 1.0, 1.0),
          setSFColor(id, 'GLight', 0.0, 1.0, 0.0).
  lights_a(Delay) :-
          sleep(Delay),
          format('~ttraffic lights, case 2~n'),
          setSFColor(id, 'ALight', 1.0, 0.9, 0.0),
          setSFColor(id, 'GLight', 1.0, 1.0, 1.0).
  lights_r(Delay) :-
          sleep(Delay),
          format('~ttraffic lights, case 3~n'),
          setSFColor(id, 'RLight', 1.0, 0.0, 0.0),
          setSFColor(id, 'ALight', 1.0, 1.0, 1.0).
  
  :-end_object object_trafficlights.