anchor.diff:      #"--${boolEn (ilbc != null)}-libilbc"
       "--disable-libilbc"
       (fflag "--${boolEn (jack2_lib != null)}-libjack" "4.0")
  +    /**/(fflag "--disable-libklvanc" "4.1")
       "--${boolEn (kvazaar != null)}-libkvazaar"
       /**/(fflag "--disable-liblensfun" "4.1")
       "--${boolEn (libmodplug != null)}-libmodplug"
  
positive.code:     "--${boolEn (x264 != null)}-libx264"
      "--${boolEn (x265 != null)}-libx265"
      "--${boolEn (xavs != null)}-libxavs"
      #"--${boolEn (libxcb != null)}-libxcb"
      "--${boolEn libxcbshmExtlib}-libxcb-shm"
      "--${boolEn libxcbxfixesExtlib}-libxcb-xfixes"
  
negative.code:     };
      "9.9" = {  # Git
        fetchzipversion = 6;
        version = "2019.02.14";
        rev = "9e1e5213933dfed529f0cecac7304236a786177e";
        sha256 = "daeb1af827a9a3331a99efb11bf57ee06dcc65eaa4fb0438469caba52d7f2620";
      };
    };
    source = sources."${channel}";
  