[Go] Void interface demo.

package main

import (
    "fmt"
)

func main() {
    var v interface{}

    // v is an integer.
    v = 1
    fmt.Println(v)

    // v becomes a string now.
    v = "Hello"
    fmt.Println(v)

    // v becomes a boolean value now.
    v = true
    fmt.Println(v)
}