anchor.diff:  in
   stdenv.mkDerivation rec {
     name = "st-0.7";
  -  
  +
     src = fetchurl {
       url = "http://dl.suckless.org/st/${name}.tar.gz";
       multihash = "QmV1FssAdXN44hWi4QjWp5GLn5ZqwqnvBjJ8JRNayMRi5Z";
  
positive.code: assert config != null -> configFile == null;
  
  let
    inherit (stdenv.lib)
      optionalString;
  
    configFile' =
  
negative.code: { stdenv
  , fetchurl
  , lib
  , writeText
  
  , freetype
  , fontconfig
  , libx11
  , libxext
  , libxft
  , libxrender
  , ncurses
  , xorgproto
  
  , config ? null
  , configFile ? null
  