{"ast_node_type":"other","tokens":[{"end":51,"kind":"keyword","start":0,"text":"t.is_keyword_case(kw::Fn,"}]}
                    t.is_keyword_case(kw::Fn, case)
                    // `$qual fn`, e.g. `const fn` or `async fn`.
                    // Two qualifiers `$qual $qual` is enough, e.g. `async unsafe`.