Function fluent_locale::negotiate::negotiate_languages

pub fn negotiate_languages<'a, R: 'a + Into<LanguageIdentifier> + Clone, A: 'a + Into<LanguageIdentifier> + PartialEq + Clone>(
    requested: impl IntoIterator<Item = &'a R>, 
    available: impl IntoIterator<Item = &'a A>, 
    default: Option<&'a A>, 
    strategy: NegotiationStrategy
) -> Vec<&A>