Val: A New Language Alternative to C++, Rust(thenewstack.io)

    subscript longer_of(_ a: inout String, _ b: inout String): String {
      if b.count() > a.count() { yield &b } else { yield &a }
    }

    fun emphasize(_ z: inout String, strength: Int = 1) {
      z.append(repeat_element("!", count: strength)))
    }

    public fun main() {
      var (x, y) = ("Hi", "World")
      emphasize(&longer_of[&x, &y])
      print("${x} ${y}") // "Hi World!"
    }