fn main() {
    a1 := [1, 2, 3, 4].map(fn (a int, b int) int {
        return a + b
    })
    println(a1)

    a2 := [1, 2, 3, 4].map(fn (a string) string {
        return a
    })
    println(a2)

    a3 := [1, 2, 3, 4].map(fn (a string) {})
    println(a3)

    a4 := [1, 2, 3, 4].map(add1)
    println(a4)

    a5 := [1, 2, 3, 4].map(add2)
    println(a5)

    a6 := [1, 2, 3, 4].map(do_nothing)
    println(a6)
}

fn add1(a int, b int) int {
    return a + b
}

fn add2(a string) string {
    return a
}

fn do_nothing(a string) {
}