I created the function in Swift and when i submit my code it passes all test except for "Multiply non-negative bytes with product less than 256". The exact error is 'XCTAssertEqual failed: ("Ã") is not equal to ("ÿ") -'. I saw the other question about code not passing this test so i changed it so my output was returned as a ISO_8859_1 return String(bytes: out_data, encoding: .isoLatin1 ) string but i am still getting exact same error. Any advice about where i have gone wrong would be much appriciated.