Function rank 

pub fn rank<'a>(
    candidates: &'a [MentionCandidate],
    query: &str,
) -> Vec<&'a MentionCandidate>

The candidates worth offering for query, best first, ranked as every list search ranks (crate::search::ranked_rows): a prefix of the whole name, then of a later word (“lov” finds “Ada Lovelace”), then the participant id. Within a rank the given order holds, so the list does not reshuffle while a name is typed. An empty query offers everyone.