code: function(sep) {
      var out = new Array(8);
      var b = this.buffer, o = this.offset;
      for (var i = 0; i < 8; i++) {
        out[i] = _HEX[b[o+i]];
      }
      return out.join(sep || '');
    }
docs: Return a string showing the buffer octets, with MSB on the left.
  
  @param sep separator string. default is '' (empty string)