The Locale interface looks like this.

    1. // Locale is the interface which returns from a `Localizer.GetLocale` metod.
    2. // It serves the transltions based on "key" or format. See `GetMessage`.
    3. type Locale interface {
    4.     // Index returns the current locale index from the languages list.
    5.     // Tag returns the full language Tag attached tothis Locale,
    6.     // it should be uniue across different Locales.
    7.     Tag() *language.Tag
    8.     // Language should return the exact languagecode of this `Locale`
    9.     //
    10.     // Same as `Tag().String()` but it's static.
    11.     Language() string
    12.     // GetMessage should return translated text based n the given "key".
    13. }