{"ast_node_type":"variable","tokens":[{"end":73,"kind":"keyword","start":0,"text":"let"}]}
    let (t, r) = parse_any_link(reference_def.as_bytes(), true).unwrap();
    let reference_def = "[see here]: docs.rs\nother";
    assert_eq!(t, MdTree::LinkDef { id: "see here", link: "docs.rs" });