anchor.diff:      };
       inherit version;
     }; in
  - {
  + rec {
     "4.04" = mkOldParam {
       version = "8.06.2";
       key = "1628";
  
positive.code:     version = "8.06.5";
      key = "1764";
      sha256 = "0wgx65y1wkgf22ihpqmspqfp95fqbj3pldhp1p3b1mi8rmc37zwj";
    };
  }.${builtins.substring 0 4 ocaml.version};
  in
  
negative.code: else
  
  let param =
    let mkNewParam = { version, sha256 }: {
      inherit version;
      src = fetchzip {
        url = "https://github.com/garrigue/labltk/archive/${version}.tar.gz";
        inherit sha256;
      };
    }; in
    let mkOldParam = { version, key, sha256 }: {
      src = fetchurl {
        url = "https://forge.ocamlcore.org/frs/download.php/${key}/labltk-${version}.tar.gz";
  