code: function CreateSetPolyfill() {
              return /** @class */ (function () {
                  function Set() {
                      this._map = new _Map();
                  }
                  Object.defineProperty(Set.prototype, "size", {
                      get: function () { return this._map.size; },
                      enumerable: true,
                      configurable: true
                  });
                  Set.prototype.has = function (value) { return this._map.has(value); };
                  Set.prototype.add = function (value) { return this._map.set(value, value), this; };
                  Set.prototype.delete = function (value) { return this._map.delete(value); };
                  Set.prototype.clear = function () { this._map.clear(); };
                  Set.prototype.keys = function () { return this._map.keys(); };
                  Set.prototype.values = function () { return this._map.values(); };
                  Set.prototype.entries = function () { return this._map.entries(); };
                  Set.prototype["@@iterator"] = function () { return this.keys(); };
                  Set.prototype[iteratorSymbol] = function () { return this.keys(); };
                  return Set;
              }());
          }
docs: naive Set shim