{"ast_node_type":"other","tokens":[{"end":56,"kind":"keyword","start":0,"text":"(Fn)"}]}
    (Fn)             => { exp!(@kw, Fn,         KwFn) };
    (Extern)         => { exp!(@kw, Extern,     KwExtern) };
    (For)            => { exp!(@kw, For,        KwFor) };