{"ast_node_type":"variable","tokens":[{"end":56,"kind":"keyword","start":0,"text":"if"}]}
        if let Some(self_param) = self.body.self_param {
        let mut param_tys = param_tys.into_iter().chain(iter::repeat(self.table.new_type_var()));
            if let Some(ty) = param_tys.next() {