{"ast_node_type":"other","tokens":[{"end":60,"kind":"keyword","start":0,"text":"(Extern)"}]}
    (Extern)         => { exp!(@kw, Extern,     KwExtern) };
    (Enum)           => { exp!(@kw, Enum,       KwEnum) };
    (Fn)             => { exp!(@kw, Fn,         KwFn) };