map keys method

---

examples/map-keys-method/map_keys_method.go

package main

import (
    "fmt"
)

type hash map[string]int

func (h hash) keys() []string {
    keys := make([]string, 0, len(h))
    for k := range h {
        keys = append(keys, k)
    }
    return keys
}

func main() {
    data := hash{
        "foo": 3,
        "bar": 17,
        "adi": 10,
    }
    fmt.Println(data)
    ks := data.keys()
    fmt.Println(ks)
}

map[adi:10 bar:17 foo:3]
[foo bar adi]