CREATING SETS
let setOne: Set<Int>
let someArray = [1, 2, 3, 1]
var someSet: Set<Int> = [1, 2, 3, 1]
print(someSet)
// > [2, 3, 1]
ACCESSING ELEMENTS
print(someSet.contains(1))
// > true
print(someSet.contains(4))
// > false
ADDING & REMOVING ELEMENTS
someSet.insert(5)
let removedElement = someSet.remove(1)
print(removedElement!)
// > 1
