Function no_na_holds_several 

fn no_na_holds_several(ty: &Type) -> bool

Whether a no_na value of Rust type ty holds several values, looking through the layers no_na checks through: Missing, Option, Result<T, _> (its T) and Either<L, R>, which holds several when either arm does. The text is fixed at compile time, before the conversion picks an arm, and contain also reads right for one value.