anchor.diff:  , zip
   }:
   
  -let
  -  inherit (stdenv.lib)
  -    optionalString;
  -in
  -
   # Pandoc is required to build the package's man page. Release tarballs
   # contain a formatted man page already, though, so it's fine to pass
   # "pandoc = null" to this derivation; the man page will still be
  
positive.code:       --prefix PATH : "${ffmpeg}/bin"
    '';
  
    # Requires network
    doCheck = false;
  
    meta = with stdenv.lib; {
      description = "CLI tool to download videos from YouTube.com & other sites";
  
negative.code: # case someone wants to use this derivation to build a Git version of
  # the tool that doesn't have the formatted man page included.
  
  let
    inherit (stdenv.lib)
      optionalString;
  
    version = "2016.08.07";
  in
  buildPythonPackage rec {
    name = "youtube-dl-${version}";
  
    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";
      allowHashOutput = false;
      sha256 = "6f42477c562291cd392b7a034a7b828bbf1e209a48de7629848ba82a3aacdc1f";
    };
  
    nativeBuildInputs = [
  