pub fn try_parse_reference_definition(
text: &str,
) -> Option<(usize, String, String, Option<String>)>Expand description
Try to parse a reference definition starting at the current position. Returns Some((length, label, url, title)) if successful.
Syntax:
[label]: url "title"
[label]: <url> 'title'
[label]: url
(title on next line)