anchor.diff:  , vncSupport ? !nixosTestRunner, libjpeg, libpng
   , smartcardSupport ? !nixosTestRunner, libcacard
   , spiceSupport ? !stdenv.isDarwin && !nixosTestRunner, spice, spice-protocol
  +, ncursesSupport ? !nixosTestRunner, ncurses
   , usbredirSupport ? spiceSupport, usbredir
   , xenSupport ? false, xen
   , cephSupport ? false, ceph
  
positive.code: { stdenv, fetchurl, fetchpatch, python, zlib, pkgconfig, glib
  , ncurses, perl, pixman, vde2, alsaLib, texinfo, flex
  , bison, lzo, snappy, libaio, gnutls, nettle, curl
  , makeWrapper
  , attr, libcap, libcap_ng
  
negative.code:   nativeBuildInputs = [ python python.pkgs.sphinx pkgconfig flex bison ]
      ++ optionals gtkSupport [ wrapGAppsHook ];
    buildInputs =
      [ zlib glib perl pixman
        vde2 texinfo makeWrapper lzo snappy
        gnutls nettle curl
      ]
      ++ optionals ncursesSupport [ ncurses ]
      ++ optionals stdenv.isDarwin [ CoreServices Cocoa Hypervisor rez setfile ]
      ++ optionals seccompSupport [ libseccomp ]
      ++ optionals numaSupport [ numactl ]
  