text: var E;
  (function (E) {
      E[E["x"] = 0] = "x";
  })(E || (E = {}));
  var x1 = null + null;
  var x2 = null + undefined;
  var x3 = undefined + null;
  var x4 = undefined + undefined;
  var x5 = 1 + null;
  var x6 = 1 + undefined;
  var x7 = null + 1;
  var x8 = undefined + 1;
  var x9 = "test" + null;
  var x10 = "test" + undefined;
  var x11 = null + "test";
  var x12 = undefined + "test";
  var x13 = null + 0 /* x */;
  var x14 = undefined + 0 /* x */;
  var x15 = 0 /* x */ + null;
  var x16 = 0 /* x */ + undefined;
  