{"ast_node_type":"function","tokens":[{"end":74,"kind":"keyword","start":0,"text":"fn"}]}
    fn param_count(&self, sig_id: DefId) -> (usize, bool /*c_variadic*/) {
    // Function parameter count, including C variadic `...` if present.
        if let Some(local_sig_id) = sig_id.as_local() {