Function text_typesetting_language 

pub fn text_typesetting_language(
    words: [u64; 4],
    language: &[u8],
    enabled: bool,
) -> ViewHandle

Text.typesettingLanguage(_:isEnabled:) with a Locale.Language.

The language goes by address in x0, isEnabled in x1, and the receiving Text’s four words follow in x2 through x5 — a Text is not self in x20 here, because this is a method on a struct that returns a new one and the compiler passes it like any other argument.