pub fn build(spanneds: &[Spanned<T>]) -> Option<Span> {
        let spans = spanneds
            .iter()
            .map(|s| s.span.clone())
            .collect::<Vec<Span>>();
        Span::join(spans)
    }
Joins a Vector of spanned items into a single span.
passerine-common/src/span.rs