[Go] Type assertion with uncertainty

package main

import (
    "fmt"
    "log"
)

func main() {
    var im interface{}
    var in interface{}

    im = 3
    in = 2

    // type assertion
    m, ok := im.(int)
    if !ok {
        log.Fatal("Wrong type")
    }

    n, ok := in.(int)
    if !ok {
        log.Fatal("Wrong type")
    }

    fmt.Println(m + n)
}