code: function (buffer, start, length) {
    /*jshint bitwise:false*/
  
    var isNested = buffer instanceof ByteBuffer;
  
    this.buffer = isNested ? buffer.buffer : buffer;
    this.start = (start || 0) + (isNested ? buffer.start : 0);
    this.length = length || (this.buffer.length - this.start);
    this.offset = 0;
  
  }
docs: wraps and reuses buffer, possibly cropped (offset, length)