Function relinked 

pub fn relinked(
    content: &str,
    stored: Option<&str>,
    metadata: &BTreeMap<String, Value>,
) -> String

content as a write of an item holding metadata stores it: with its ## Links section re-rendered from the links metadata holds, so a content write never drops what a person sees of them.

Each link keeps the line stored — the content as the source stores it now, its section included — already shows it with, so its other end’s title and address survive; a link the stored section does not show gets link_line. content already ending in a section — a link write’s own — is answered unchanged, and so is any content of an item holding no links, so a write of an item that never had one is exactly what it was.