{"ast_node_type":"variable","tokens":[{"end":49,"kind":"keyword","start":0,"text":"let"}]}
                let late_bound_in_projection_ty =
                //     for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok
                    tcx.collect_constrained_late_bound_regions(projection_term);