{"ast_node_type":"variable","tokens":[{"end":55,"kind":"keyword","start":0,"text":"let"}]}
    let clif_ty = fx.clif_type(a.layout().ty).unwrap();
    // c + carry -> c + second intermediate carry or borrow respectively
    let cb_in_as_int = fx.bcx.ins().uextend(clif_ty, cb_in);