anchor.diff:    /**
      * Return a InputBuffer to read a subset of this buffer.
      * If [position] is not specified, the current read position is
  -   * used.  If [length] is not specified, the remainder of this buffer is used.
  +   * used. If [length] is not specified, the remainder of this buffer is used.
      */
     InputBuffer subset([int position, int length]) {
       if (position == null || position < 0) {
  
positive.code: part of archive;
  
  class InputBuffer {
    List<int> buffer;
    int position = 0;
    final int byteOrder;
  
  
negative.code: 
      return new InputBuffer(buffer.sublist(position, end),
                             byteOrder: byteOrder);
    }
  
    /**
     * Read [count] bytes from an [offset] of the current read position, without
     * moving the read position.
     */
    List<int> peekBytes(int count, [int offset = 0]) {
      List<int> bytes = buffer.sublist(position + offset,
                                       position + offset + count);
      return bytes;
    }
  
    /**
  