[Go] Check the existence of some key in map.

package main

import (
    "log"
)

func main() {
    m := make(map[string]string)

    m["Go"] = "Beego"
    m["Python"] = "Django"
    m["Ruby"] = "Rails"
    m["PHP"] = "Laravel"

    v, ok := m["Go"]
    if !ok {
        log.Fatal("It should be true")
    }

    if !(v == "Beego") {
        log.Fatal("Wrong value")
    }

    _, ok = m["Java"]
    if !(ok == false) {
        log.Fatal("It should be false")
    }
}