pub fn sort(&mut self) {
        self.per_file
            .par_iter_mut()
            .for_each(|(_origin, suggestions)| {
                suggestions.sort_by(|a, b| {
                    let cmp = a.span.start.cmp(&b.span.start);
                    if cmp != std::cmp::Ordering::Equal {
                        return cmp;
                    }

                    a.span.end.cmp(&b.span.end)
                });
            });
        self.per_file
            .sort_by(|origin_a, _a, origin_b, _b| -> std::cmp::Ordering {
                origin_a.as_path().cmp(origin_b.as_path())
            });
    }
Sorts the files in alphabetical order, then sorts the per-file
suggestions based on start and end spans.
src/suggestion.rs