{"ast_node_type":"other","tokens":[{"end":64,"kind":"keyword","start":0,"text":"stalled_vars.retain(|arg|"}]}
                    stalled_vars.retain(|arg| match arg.kind() {
                    // Remove the canonicalized universal vars, since we only care about stalled existentials.
                        ty::GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Infer(_)),