{"ast_node_type":"variable","tokens":[{"end":91,"kind":"keyword","start":0,"text":"let"}]}
                let msb = fx.bcx.ins().iconst(types::I64, (const_val >> 64) as u64 as i64);
                let lsb = fx.bcx.ins().iconst(types::I64, const_val as u64 as i64);
                fx.bcx.ins().iconcat(lsb, msb)