anchor.diff:    inherit (stdenv.lib)
       optionalString;
   
  -  version = "2016.09.11.1";
  +  version = "2016.10.19";
   in
   buildPythonPackage rec {
     name = "youtube-dl-${version}";
  
positive.code:   src = fetchurl {
      url = "https://github.com/rg3/youtube-dl/releases/download/"
        + "${version}/${name}.tar.gz";
      sha512Url = "https://github.com/rg3/youtube-dl/releases/download/"
        + "${version}/SHA2-512SUMS";
      hashOutput = false;
      sha256 = "6cdeb0876295bef0325b8433c47c1ed13ebab3b108ef5ee27171e06b6958cb35";
    };
  
    nativeBuildInputs = [
  
negative.code:       inherit (src)
          outputHash
          outputHashAlgo
          urls;
        sha512Url = "https://github.com/rg3/youtube-dl/releases/download/"
          + "${version}/SHA2-512SUMS";
        pgpsigUrls = map (n: "${n}.sig") src.urls;
        # Sergey M.
        pgpKeyFingerprint = "ED7F 5BF4 6B3B BED8 1C87  368E 2C39 3E0F 18A9 236D";
        failEarly = true;
      };
    };
  
  