anchor.diff:  }:
   
   let
  -  version = "4.5.2";
  +  version = "4.5.4";
   
     src = fetchFromGitHub {
       owner = "opencv";
       repo = "opencv";
       rev = version;
  -    sha256 = "sha256-pxi1VBF4txvRqspdqvCsAQ3XKzl633/o3wyOgD9wid4=";
  +    sha256 = "sha256-eIESkc/yYiZZ5iY4t/rAPd+jfjuMYR3srCBC4fO3g70=";
     };
   
     contribSrc = fetchFromGitHub {
       owner = "opencv";
       repo = "opencv_contrib";
       rev = version;
  -    sha256 = "sha256-iMenRTY+qeL7WRgnRuQbsHflYDakE7pWWSHeIjrg0Iw=";
  +    sha256 = "sha256-RkCIGukZ8KJkmVZQAZTWdVcVKD2I3NcfGShcqzKhQD0=";
     };
   
     # Contrib must be built in order to enable Tesseract support:
  
positive.code:   # Ensures that we use the system OpenEXR rather than the vendored copy of the source included with OpenCV.
    patches = [
      ./cmake-don-t-use-OpenCVFindOpenEXR.patch
      # Fix usage of deprecated version of protobuf' SetTotalBytesLimit. Remove with the next release.
      (fetchpatch {
        url = "https://github.com/opencv/opencv/commit/384875f4fcf1782b10699a379aa245a03cb27a04.patch";
        sha256 = "1agwd0pm07m2dy8a62vmfl4n73dsmsdll2a73q6kara9wm3jlp41";
      })
    ] ++ lib.optional enableCuda ./cuda_opt_flow.patch;
  
    # This prevents cmake from using libraries in impure paths (which
  
negative.code: { lib
  , stdenv
  , fetchurl
  , fetchFromGitHub
  , cmake
  , pkg-config
  