anchor.diff:          member t.Set d = r := d}
   
       member z.Prim (_: Prim<'t>) = downNone<'w, 't>
  +
       member z.Unsupported (_: Unsupported<'t>) =
  -      printfn "WARNING: Type %A may not be properly supported by Zipper." typeof<'t>
  +      if warned.ContainsKey typeof<'t> |> not then
  +        warned.[typeof<'t>] <- ()
  +        printfn "WARNING: Type %A is seen as primitive by Zipper." typeof<'t>
         downNone<'w, 't>
   
       member z.String () : Down<'w, string> =
  
positive.code:     abstract Un: byref<'v> * byref<'h> * byref<'n> * byref<'p> -> unit
  
    type [<InferenceRules>] Zipper () =
      member z.ToZipper (_: Rep, wD: Down<'w, 'w>) =
        {new Up<'w, 'w> () with
          member u.Up w =
  
negative.code: namespace Infers.Toys
  
  module Zipper =
    open System.Collections.Generic
    open System
    open Infers
    open Infers.Rep
  
  