{"ast_node_type":"function","tokens":[{"end":81,"kind":"keyword","start":0,"text":"fn"}]}
    fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef) {
impl EarlyLintPass for KeywordIdents {
        self.check_tokens(cx, &mac_def.body.tokens);