anchor.diff:      (enableFeature (fribidi != null) "libfribidi")
       (enableFeature (game-music-emu != null) "libgme")
       (enableFeature (gnutls != null) "gnutls")
  -    (enableFeature (gsm != null) "libgsm")
  +    #(enableFeature (gsm != null) "libgsm")
       #(enableFeature (ilbc != null) "libilbc")
       (enableFeature (ladspaH !=null) "ladspa")
       (enableFeature (lame != null) "libmp3lame")
  
positive.code: 
  stdenv.mkDerivation rec {
    name = "ffmpeg-full-${version}";
    version = "2.8.1";
  
    src = fetchurl {
      url = "https://www.ffmpeg.org/releases/ffmpeg-${version}.tar.bz2";
      sha256 = "1qk6g2h993i0wgs9d2p3ahdc5bqr03mp74bk6r1zj6pfinr5mvg2";
    };
  
    patchPhase = ''patchShebangs .'';
  
    configureFlags = [
      /*
  
negative.code: , optimizationsDeveloper ? true
  , extraWarningsDeveloper ? false
  , strippingDeveloper ? false
  
  , ffmpeg
  }:
  
  /* Maintainer notes:
  