anchor.diff:    src = fetchurl {
       url = "https://github.com/libusb/libusb/releases/download/v${version}/"
         + "${name}.tar.bz2";
  -    sha256 = "7dce9cce9a81194b7065ee912bcd55eeffebab694ea403ffb91b67db66b1824b";
  +    sha256 = "75aeb9d59a4fdb800d329a545c2e6799f732362193b465ea198f2aa275518157";
     };
   
     buildInputs = [
  
positive.code:   inherit (stdenv.lib)
      optional;
  
    version = "1.0.21";
  in
  stdenv.mkDerivation rec {
    name = "libusb-${version}";
  
negative.code:   ];
  
    configureFlags = [
      "--enable-udev"
      "--enable-timerfd"
    ];
  
    NIX_LDFLAGS = [
  