anchor.diff:  stdenv.mkDerivation rec {
     name = "libevent-${version}";
   
  -  /*src = fetchurl {
  +  src = fetchurl {
       urls = tarballUrls version;
       hashOutput = false;
  -    sha256 = "18qz9qfwrkakmazdlwxvjmw8p76g70n3faikwvdwznns1agw9hki";
  -  };*/
  -
  -  src = fetchFromGitHub {
  -    version = 2;
  -    owner = "libevent";
  -    repo = "libevent";
  -    rev = "release-${version}";
  -    sha256 = "70a1e1042a1035f2e0d0d2edcb5eae84ca718b69a26803bebf6115e72dd5db41";
  +    sha256 = "965cc5a8bb46ce4199a47e9b2c9e1cae3b137e8356ffdad6d94d3b9069b71dc2";
     };
   
     nativeBuildInputs = [
  -    autoreconfHook
       python
     ];
   
  
positive.code: { stdenv
  , autoreconfHook
  , fetchFromGitHub
  , python
  
  , openssl
  }:
  
  let
    version = "2.1.7-rc";
  
    tarballUrls = version: [
      "https://github.com/libevent/libevent/releases/download/release-${version}-stable/libevent-${version}-stable.tar.gz"
  
negative.code:     "--disable-samples"
    ];
  
    passthru = {
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "2.1.8";
        pgpsigUrls = map (n: "${n}.asc") urls;
        pgpKeyFingerprints = [
          "9E3A C83A 2797 4B84 D1B3  401D B860 8684 8EF8 686D"
        ];
        inherit (src) outputHashAlgo;
        outputHash = "965cc5a8bb46ce4199a47e9b2c9e1cae3b137e8356ffdad6d94d3b9069b71dc2";
      };
    };
  
    meta = with stdenv.lib; {
      description = "Event notification library";
  