anchor.diff: -{ lib, stdenv, fetchurl, autoconf, automake, libtool, pkgconfig, zlib, ilmbase }:
  +{ lib, stdenv, fetchurl, fetchpatch, autoconf, automake, libtool, pkgconfig, zlib, ilmbase }:
   
   stdenv.mkDerivation rec {
     name = "openexr-${lib.getVersion ilmbase}";
  
positive.code:     url = "http://download.savannah.nongnu.org/releases/openexr/${name}.tar.gz";
      sha256 = "0ca2j526n4wlamrxb85y2jrgcv0gf21b3a19rr0gh4rjqkv1581n";
    };
  
    outputs = [ "bin" "dev" "out" "doc" ];
  
  
negative.code: 
    enableParallelBuilding = true;
  
    meta = with stdenv.lib; {
      homepage = http://www.openexr.com/;
      license = licenses.bsd3;
  