     
     func testMaskingRightShiftEqualOperator() {
         var thing = UInt128()
-        thing &>>= UInt128(1)
+        thing &>>= UInt128(upperBits: 0, lowerBits: 1)
         XCTFail("Test not written yet.")
     }
     
     func testMaskingLeftShiftEqualOperator() {
         var thing = UInt128()
-        thing &<<= UInt128(1)
+        thing &<<= UInt128(upperBits: 0, lowerBits: 1)
         XCTFail("Test not written yet.")
     }
 }

    
    func testCanBeSentToAnInt() {
        let expectedResult: Int = 1
        let testResult = Int(UInt128(1))
        XCTAssertEqual(testResult, expectedResult)
    }
    

    
    func testSignBitIndex() {
        let tests = [
            (input: UInt128(), output: Int(127)),
            (input: UInt128.max, output: Int(0))]
        
        tests.forEach { test in
