anchor.diff:          this.bits = bits;
           return;
         }
  -    }
  +    }   
     }
     
     int get numColors {
       return table.length ~/ 3;
  -  }
  +  }  
   }
   
   List<int> _header(int width, int height, int colorBits) {
  
positive.code:   /**
     * Pads the color table with zeros to the next power of 2 and sets bits.
     */
    void finish() {
      for (int bits = 1;; bits++) {
        int colors = 1 << bits;
        if (colors * 3 >= table.length) {
  
negative.code:     bytes.addAll(colors.table);
      bytes.addAll(_loop(0));
      
      for (int i = 0; i < _frames.length; i++) {
        var frame = _frames[i];
        bytes
          ..addAll(_delayNext(delay))
          ..addAll(_startImage(0, 0, width, height))
  