{"ast_node_type":"other","tokens":[{"end":52,"kind":"keyword","start":0,"text":"///"}]}
///     body of a macro rule -- just in the pattern.
///     `$id:ident`. In this example, `expr` and `ident` are "matchers". They are not present in the
///   - Metavariable expressions are only valid in the "body", not the "pattern".