Passing a function as a parameter - Callback function

---

As it is right now, the run function can only accept callback functions without any parameter

examples/callback-function/callback_function.go

package main

import (
    "fmt"
)

func main() {
    run(hello)
    run(world)
}

func hello() {
    fmt.Println("Hello")
}

func world() {
    fmt.Println("World!")
}

func run(f func()) {
    f()
}