     context 'filter', ->
       type.is -> 'filter'
       rootValue.is -> '2,5,9,10'
-      opValue.is -> 'return value % 2 == 0'
+      opValue.is -> 'function(value) { return value % 2 == 0 }'
 
       it 'has correct values', ->
         expect(subject()).toEqual [

      rootValue.is -> '{50: 1, 90: 2, 100: 3, 201: 4, 205: 5}'
      opValue.is -> '100'

      it.only 'has correct values', ->
        expect(subject()).toEqual [
          onNext(300, [1,2])
          onNext(400, [3])


  subject = ->
    scheduler = new Rx.TestScheduler
    observableFactory = Visualizer.buildObservable(uiValuator, {})(structure())

    observable = observableFactory[targetId()](scheduler)
    results = scheduler.startWithCreate R.always(observable)
    results.messages
