{"ast_node_type":"variable","tokens":[{"end":70,"kind":"keyword","start":0,"text":"let"}]}
        let fn_trait_kind = self.fn_trait_kind_from_trait_id(trait_)?;
        // for closures and async closures, respectively.
        if !matches!(closure_kind, ClosureKind::Closure | ClosureKind::Async) {