 
 extension ObservableBlockingTest {
     func testLast_empty() {
-        XCTAssertNil(try! Observable<Int>.empty().toBlocking().last())
+        XCTAssertNil(try Observable<Int>.empty().toBlocking().last())
     }
     
     func testLast_return() {
-        XCTAssertEqual(try! Observable.just(42).toBlocking().last(), 42)
+        XCTAssertEqual(try Observable.just(42).toBlocking().last(), 42)
     }
     
     func testLast_fail() {

    }
    
    func testSingle_return() {
        XCTAssertEqual(try! Observable.just(42).toBlocking().single(), 42)
    }

    func testSingle_two() {

    }
    
    func testToArray_someData() {
        XCTAssertEqual(try Observable.of(42, 43, 44, 45).toBlocking().toArray(), [42, 43, 44, 45])
    }
    
    func testToArray_withRealScheduler() {
