func (country *Country) All() map[string]interface{} {
	return country.readCountriesDataFile().data
}
All will return all countries name and dialing code
package country
import (
	"encoding/json"
	"io/ioutil"
	"path/filepath"
)
type Country struct {
	data map[string]interface{}
}
func NewCountry() *Country {
	instance := &Country{}
	instance = instance.readCountriesDataFile()
	return instance
}
func (country *Country) readCountriesDataFile() *Country {
	if len(country.data) > 0 {
		return country
	}
	dataPath, _ := filepath.Abs("./data/countries.json")
	file, _ := ioutil.ReadFile(dataPath)
	json.Unmarshal([]byte(file), &country.data)
	return country
}