anchor.diff:          let p = oref 0
   
           p <~ 5
  -        Assert.True(!!p = 5)
  +        Assert.Equal(5, !!p)
   
           p <~ 6
  -        Assert.True(!!p = 6)
  +        Assert.Equal(6, !!p)
   
       [<Fact>]
       let ``property changes should be observed correctly`` () =
  
positive.code: 
          let binding = (a.AsProperty(0), id) @~> b
  
          Assert.True(!!b = 4)
  
      [<Fact>]
      let ``converting IObserver to IWriteableProperty works`` () =
  
negative.code:         let binding = (a, id) @~> b
  
          a <~ 5
          Assert.Equal(5, !!b)
  
          a <~ 6
          Assert.Equal(6, !!b)
  
          binding.Dispose()
  
          a <~ 7
          Assert.Equal(6, !!b)
  
      [<Fact>]
      let ``two-way binding should work`` () =
  