anchor.diff:    buildInputs = [
       hostname
       python2 time # coq-makefile timing tools
  +    jbuilder
     ]
     ++ (with ocamlPackages; [ ocaml findlib camlp5_strict num ])
     ++ optional buildIde ocamlPackages.lablgtk
  
positive.code: 
  { pkgs ?
      (import (fetchTarball {
        url = "https://github.com/NixOS/nixpkgs/archive/060a98e9f4ad879492e48d63e887b0b6db26299e.tar.gz";
        sha256 = "1lzvp3md0hf6kp2bvc6dbzh40navlyd51qlns9wbkz6lqk3lgf6j";
      }) {})
  , ocamlPackages ? pkgs.ocaml-ng.ocamlPackages_4_06
  , buildIde ? true
  
negative.code:     else
        with builtins; filterSource
          (path: _:
             !elem (baseNameOf path) [".git" "result" "bin" "_build" "_build_ci"]) ./.;
  
    prefixKey = "-prefix ";
  
  