let chars: Set<Character> = ["A", "B", "C", "D"]
let containA = chars.contains("A")
//containA is true

let containE = chars.contains("E")
//containE is False

let chars2: Set<Character> = ["A", "B"]
let containAll = chars.isSuperset(of: chars2)
//containAll is true

print("containA is \(containA)")
print("containE is \(containE)")
print("containAll is \(containAll)")