anchor.diff:  
     patches = [
       ./nomacs-iostream.patch
  +    (fetchpatch {
  +      name = "darwin-less-restrictive-opencv.patch";
  +      url = "https://github.com/nomacs/nomacs/commit/d182fce4bcd9a25bd15e3de065ca67849a32458c.patch";
  +      sha256 = "0j6sviwrjn69nqf59hjn30c4j838h8az7rnlwcx8ymlb21vd9x2h";
  +      stripLen = 1;
  +    })
     ];
   
     enableParallelBuilding = true;
  
positive.code: , qtsvg
  
  , exiv2
  , opencv
  , libraw
  , libtiff
  , quazip
  
negative.code: { stdenv
  , mkDerivation
  , fetchFromGitHub
  , fetchpatch
  , cmake
  , pkgconfig
  
  