anchor.diff:        dtc
         flex
         openssl
  -      (buildPackages.python2.withPackages (p: [ p.libfdt ]))
  +      (buildPackages.python3.withPackages (p: [ p.libfdt ]))
         swig
       ];
       depsBuildBuild = [ buildPackages.stdenv.cc ];
  
positive.code: }:
  
  let
    defaultVersion = "2019.10";
    defaultSrc = fetchurl {
      url = "ftp://ftp.denx.de/pub/u-boot/u-boot-${defaultVersion}.tar.bz2";
      sha256 = "053hcrwwlacqh2niisn0zas95zkbffw5aw5sdhixs8lmfdq60vcd";
    };
    buildUBoot = {
      version ? null
  
negative.code: 
      src = if src == null then defaultSrc else src;
  
      patches = extraPatches;
  
      postPatch = ''
        patchShebangs tools
  