anchor.diff:  , wxSupport ? false, mesa ? null, wxGTK ? null, xlibs ? null }:
   
   assert wxSupport -> mesa != null && wxGTK != null && xlibs != null;
  +
  +with stdenv.lib;
   
   stdenv.mkDerivation rec {
     name = "erlang-" + version;
  
positive.code: 
    buildInputs =
      [ perl gnum4 ncurses openssl makeWrapper
      ] ++ stdenv.lib.optional wxSupport [ mesa wxGTK xlibs.libX11 ];
  
    patchPhase = '' sed -i "s@/bin/rm@rm@" lib/odbc/configure erts/configure '';
  
  
negative.code:     sed -e s@/bin/pwd@pwd@g -i otp_build
    '';
  
    configureFlags= "--with-ssl=${openssl} ${optionalString stdenv.isDarwin "--enable-darwin-64bit"}";
  
    postInstall = ''
      ln -s $out/lib/erlang/lib/erl_interface*/bin/erl_call $out/bin/erl_call
  