{"ast_node_type":"variable","tokens":[{"end":49,"kind":"keyword","start":0,"text":"let"}]}
    let (_, rhs_high) = fx.bcx.ins().isplit(rhs);
    let (low, lhs_high) = fx.bcx.ins().isplit(lhs);
    let high = fx.bcx.ins().band_imm(lhs_high, 0x7fff_ffff_ffff_ffff_u64 as i64);