pub fn locales(mut self, default: &str, other: &[&str]) -> Self {
        self.locales = Locales {
            default: default.to_string(),
            other: other.iter().map(|s| s.to_string()).collect(),
            using_i18n: true,
        };
        self
    }
Sets the locales information for the app. The first argument is the
default locale (used as a fallback for users with no locale preferences
set in their browsers), and the second is a list of other locales
supported.

Note that this does not update the translations manager, which must be
done separately (if you're using [`FsTranslationsManager`], the default,
you can use `.locales_and_translations_manager()` to set both at
once).

If you're not using i18n, you don't need to call this function. If you
for some reason do have to though (e.g. overriding some other
preferences in middleware), use `.disable_i18n()`, not this, as
you're very likely to shoot yourself in the foot! (If i18n is disabled,
the default locale MUST be set to `xx-XX`, for example.)
packages/perseus/src/init.rs