anchor.diff:              use binding = (a, id) <~@~> (b, id)
   
               a <~ 5
  -            Assert.True(!!b = 5)
  +            Assert.Equal(5, !!b)
               b <~ 6
  -            Assert.True(!!a = 6)
  +            Assert.Equal(6, !!a)
   
           a <~ 7
  -        Assert.True(!!b = 6)
  +        Assert.Equal(6, !!b)
   
       [<Fact>]
       let ``binding an observable to property should work`` () =
  
positive.code: 
          let vals = o.Take(3).ToEnumerable() |> Array.ofSeq
  
          Assert.True([| 1; 2; 3 |] = vals)
  
negative.code:         let p = oref 0
  
          p <~ 5
          Assert.Equal(5, !!p)
  
          p <~ 6
          Assert.Equal(6, !!p)
  
      [<Fact>]
      let ``property changes should be observed correctly`` () =
  