anchor.diff:      owner = "NixOS";
       repo = "systemd";
       rev = "nixos-v${version}";
  -    sha256 = "0grcf0x793k1jx4bx7p63h3f3cd8w262824mzf8iwdsy6y9wzylr";
  +    sha256 = "0ldyhfxdy4qlgygvpc92wp0qp6p1c9y3rnm77zwbkga48x60d9i8";
     };
   
     outputs = [ "out" "lib" "man" "dev" ];
  
positive.code:   # in a backwards-incompatible way.  If the interface version of two
    # systemd builds is the same, then we can switch between them at
    # runtime; otherwise we can't and we need to reboot.
    passthru.interfaceVersion = 2;
  
    meta = with stdenv.lib; {
      homepage = http://www.freedesktop.org/wiki/Software/systemd;
  
negative.code: }:
  
  stdenv.mkDerivation rec {
    version = "242";
    name = "systemd-${version}";
  
    # When updating, use https://github.com/systemd/systemd-stable tree, not the development one!
  