pub fn _rust_i18n_lookup_fallback(locale: &str) -> Option<&str>Expand description
Lookup fallback locales
For example: "zh-Hant-CN-x-private1-private2" -> "zh-Hant-CN-x-private1" -> "zh-Hant-CN" -> "zh-Hant" -> "zh".
https://datatracker.ietf.org/doc/html/rfc4647#section-3.4