anchor.diff:  
   let
     onOff = value: if value then "ON" else "OFF";
  -  tex = texlive.combine {
  -    inherit (texlive)
  -      scheme-medium varwidth multirow hanging adjustbox collectbox stackengine
  -      sectsty tocloft newunicodechar etoc;
  -  };
   in
   stdenv.mkDerivation rec {
     pname = "fltk";
  
positive.code: 
      # Docs
      "-DOPTION_BUILD_HTML_DOCUMENTATION=${onOff withDocs}"
      "-DOPTION_BUILD_PDF_DOCUMENTATION=${onOff withDocs}"
      "-DOPTION_INSTALL_HTML_DOCUMENTATION=${onOff withDocs}"
      "-DOPTION_INSTALL_PDF_DOCUMENTATION=${onOff withDocs}"
      "-DOPTION_INCLUDE_DRIVER_DOCUMENTATION=${onOff withDocs}"
    ];
  
  
negative.code:   ] ++ lib.optionals withDocs [
      doxygen
      graphviz
    ];
  
    buildInputs = lib.optionals stdenv.hostPlatform.isDarwin [
  