anchor.diff:  { stdenv
  -, fetchurl
  +, autoreconfHook
  +, fetchFromGitHub
   , python
   
   , openssl
   }:
   
   let
  -  version = "2.0.22";
  +  version = "2.1.7-rc";
   
     tarballUrls = version: [
       "https://github.com/libevent/libevent/releases/download/release-${version}-stable/libevent-${version}-stable.tar.gz"
  
positive.code:       inherit (src) outputHashAlgo;
        outputHash = "18qz9qfwrkakmazdlwxvjmw8p76g70n3faikwvdwznns1agw9hki";
      };
    };
  
    meta = with stdenv.lib; {
      description = "Event notification library";
  
negative.code: stdenv.mkDerivation rec {
    name = "libevent-${version}";
  
    /*src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "18qz9qfwrkakmazdlwxvjmw8p76g70n3faikwvdwznns1agw9hki";
    };*/
  
    src = fetchFromGitHub {
      version = 2;
      owner = "libevent";
      repo = "libevent";
      rev = "release-${version}";
      sha256 = "70a1e1042a1035f2e0d0d2edcb5eae84ca718b69a26803bebf6115e72dd5db41";
    };
  
    nativeBuildInputs = [
      autoreconfHook
      python
    ];
  
  