anchor.diff:  , libGL ? null
   , libGLU ? null
   , wxGTK ? null
  -, wxmac ? null
   , xorg ? null
   , parallelBuild ? false
   , systemd
  
positive.code: 
  let
    inherit (lib) optional optionals optionalAttrs optionalString;
    wxPackages2 = if stdenv.isDarwin then [ wxmac ] else wxPackages;
  
  in
  stdenv.mkDerivation ({
  
negative.code: }:
  
  assert wxSupport -> (if stdenv.isDarwin
  then wxGTK != null
  else libGL != null && libGLU != null && wxGTK != null && xorg != null);
  
  assert odbcSupport -> unixODBC != null;
  