anchor.diff: +// cf.: https://github.com/mrdoob/three.js/blob/dev/src/loaders/JSONLoader.js
  +//      https://github.com/mrdoob/three.js/wiki/JSON-Model-format-3
  +
   import 'dart:io';
   import 'dart:convert';
   import 'package:args/args.dart';
  
positive.code:   }
    List<int> faces = json["faces"];
    List bones = json["bones"];
    List<int> skinIndices = json["skinIndices"];
    List<double> skinWeights = json["skinWeights"];
    Map animation = json["animation"];
  
negative.code:   print("skinIndices: ${skinIndices.length} ${skinIndices.length ~/ 2}");
    print("skinWeigths: ${skinWeights.length}");
    print("animation: ${animation['name']}");
    for (Map m in morphTargets) {
       print("morphTarget: ${m['name']} ${m['vertices'].length}");
    }
  }
  
  void main(List<String> arguments) {
  