var Ref = /*#__PURE__*/function () {
  "use strict";

  function Ref() {
    var id = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : ++Ref.nextID;
    babelHelpers.classCallCheck(this, Ref);
    this.id = id;
  }

  return Ref;
}();

Ref.nextID = 0;