anchor.diff:    buildInputs = [ makeWrapper zip ] ++ optional generateManPage pandoc;
   
     # Ensure ffmpeg is available in $PATH for post-processing & transcoding support.
  +  # rtmpdump is required to download files over RTMP
     # atomicparsley for embedding thumbnails
     postInstall = let
  -    packagesthatwillbeusedbelow = [ atomicparsley ] ++ optional ffmpegSupport ffmpeg;
  +    packagesthatwillbeusedbelow = [ atomicparsley ] ++ optional ffmpegSupport ffmpeg ++ optional rtmpSupport rtmpdump;
     in ''
       wrapProgram $out/bin/youtube-dl --prefix PATH : "${makeBinPath packagesthatwillbeusedbelow}"
     '';
  
positive.code: { stdenv, fetchurl, buildPythonApplication, makeWrapper, zip, ffmpeg, pandoc
  , atomicparsley
  # Pandoc is required to build the package's man page. Release tarballs contain a
  # formatted man page already, though, it will still be installed. We keep the
  
negative.code: # included.
  , generateManPage ? false
  , ffmpegSupport ? true
  , rtmpSupport ? true
  }:
  
  with stdenv.lib;
  