func numberInVowels(in string: String)-> Int {
    var numberOFVowels:String = ""
    for character in string.lowercased() {
        switch character {
        case "a": numberOFVowels += String(character)
        case "e": numberOFVowels += String(character)
        case "i": numberOFVowels += String(character)
        case "o": numberOFVowels += String(character)
        case "u": numberOFVowels += String(character)
        default:  print("")
        }
    }

    return numberOFVowels.count
}