{"ast_node_type":"variable","tokens":[{"end":57,"kind":"keyword","start":0,"text":"let"}]}
                let result = self.unary_op(un_op, &val)?;
                let val = self.read_immediate(&self.eval_operand(operand, Some(dest.layout))?)?;
                assert_eq!(result.layout, dest.layout, "layout mismatch for result of {un_op:?}");