         let expectation = expectationWithDescription("async test")
         var finished = 0
         let count = 512
-        var set1: NSMutableSet!
-        var set2: NSMutableSet!
+        var set1: Set<String>!
+        var set2: Set<String>!
 
         dispatch_async(queue) { [weak expectation] in
             set1 = self.getSet(count)

        }
    }

    private func getSet(count: Int) -> NSMutableSet {
        var set = NSMutableSet()
        for index in 1...count {
            let value = self.flakeGen.nextStringID()
            set.addObject(value)
        }
        return set
    }

    }

    func testStringID() {
        XCTAssertEqual(11, count(flakeGen.nextStringID()))
    }

    func testLexicalCompare() {
