anchor.diff:  
   type FSharpLazy = 
       static member Create (v: _ Func) = Lazy.Create v.Invoke
  -    static member CreateFromValue v = Lazy.CreateFromValue v
  +    static member CreateFromValue v = Lazy.CreateFromValue v
positive.code: [<Extension>]
  type FSharpChoice =
  
      [<Extension>]
      static member Match (c, f1: Func<_,_>, f2: Func<_,_>) =
          match c with
  
negative.code: 
      [<Extension>]
      static member Ap (f: Choice<Func<_,_>, _>, x) =
          f
          |> Choice.map (fun a -> a.Invoke)
          |> Choice.ap x
  
      [<Extension>]
      static member SelectSecond (o, f: Func<_,_>) = Choice.mapSecond f.Invoke o
  
      // validation
  
  