 
     func testNotProperty() {
         let source = MutableProperty(false)
-        let not = NotProperty(property: source)
+        let not = source.not()
 
         var current: Bool!
         not.producer.startWithNext { current = $0 }


    func testOrProperty() {
        let lhs = MutableProperty(true), rhs = MutableProperty(true)
        let or = OrProperty(lhs: lhs, rhs: rhs)

        var current: Bool!
        or.producer.startWithNext { current = $0 }


    func testAndProperty() {
        let lhs = MutableProperty(false), rhs = MutableProperty(false)
        let and = lhs.and(rhs)

        var current: Bool!
        and.producer.startWithNext { current = $0 }
