anchor.diff:  /// contain raw byte sequences, tag values etc. use the builder classes.
   class Encoder {
     /// Construction
  -  Encoder(Output out, {this.allowByteArrayKeys = true}) {
  +  Encoder(Output out) {
       _out = out;
       _builderHook = nullBuilderHook;
     }
  -
  -  /// The output buffer
  -  @protected
  -  final bool allowByteArrayKeys;
   
     /// The output buffer
     @protected
  
positive.code:   /// Byte string primitive.
    void writeBuff(typed.Uint8Buffer data, [bool indefinite = false]) {
      _writeBuff(data, indefinite);
      if (allowByteArrayKeys) {
        _builderHookImpl(true, data);
      } else {
        _builderHookImpl(false);
      }
    }
  
    void _writeBuff(typed.Uint8Buffer data, [bool indefinite = false]) {
  
negative.code:     final dynamic keys = value.keys;
      var keysValid = true;
      for (final dynamic element in keys) {
        if (!(element is int) && !(element is String) && !(element is typed.Uint8Buffer)) {
          keysValid = false;
          break;
        }
  