#String
"Hi".length()
// → 2
let string = "A B C"
string.explode(" ")
// → ["A", "B", "C"]
String.random(length: 5)
// → fja92
let str = "Hello"
println(str[1])
// → e
let str = "Hello"
println(str[0..2])
// → He
println(str[0...2])
// → Hel
println("A" * 3)
// → AAA