anchor.diff:  
       [<Fact>]
       let ``one-way binding should work`` () =
  -        let a = new ObservableProperty<_>(0)
  -        let b = new ObservableProperty<_>(0)
  +        let a = oref 0
  +        let b = oref 0
   
           let binding = (a, id) @~> b
   
  
positive.code: 
      [<Fact>]
      let ``a property should correctly return the stored value`` () =
          let p = new ObservableProperty<_>(0)
  
          p <~ 5
          Assert.True(!!p = 5)
  
negative.code: 
      [<Fact>]
      let ``property behavior should yield the current value first`` () =
          let p = oref 0
          p <~ 5
  
          let o = record p.Behavior
  