anchor.diff:  let insertWithArb x = Prop.forAll orderedList (fun xs -> ordered(insert x xs))
   Check.Quick insertWithArb
   
  -(**    [lang=csharp,file=../csharp/Properties.cs,key=insertWithArb] *)
  +(**
  +    [lang=csharp,file=../csharp/Properties.cs,key=insertWithArb] *)
   
   (***include-output:insertWithArb***)
   
  
positive.code: (***include-output: eager***)
  
  (**
  Lazy evaluation is needed here to make sure the propery is checked correctly:*)
  
  (***define-output: lazy***)
  let moreLazy a = a <> 0 ==> (lazy (1/a = 1/a))
  Check.Quick moreLazy
  
  (***include-output: lazy***)
  
  (** The fluent API does not have this gotcha, it is lazy by default:
  
      [lang=csharp,file=../csharp/Properties.cs,key=lazy]
  
  works as expected.
     
  ## Quantified Properties
  
  Properties may take the form `forAll <arbitrary>  (fun <args> -> <property>)`.
  
negative.code:       |> Prop.collect (List.length xs)
  Check.Quick insertCollect
  
  (**
      [lang=csharp,file=../csharp/Properties.cs,key=insertCollect]
  
  The argument of collect is evaluated in each test case, and the distribution of 
  values is reported. The type of this argument is printed using `sprintf "%A"`:*)
  