docs: function Instruction(pi) {
    _classCallCheck(this, Instruction);
  
    this.tag = pi.split('<?')[1].split(' ')[0];
    this.att = Object.create(null);
    var hit,
        atexp = Instruction._ATEXP;
  
    while (hit = atexp.exec(pi)) {
      var n = hit[1],
          v = hit[2];
      this.att[n] = cast(v);
    }
  }