···1616 self.arena_allocator.deinit();
1717}
1818```
1919+2020+## Use cases
2121+2222+- A short-lived scratch space storing intermediate results in a function,
2323+ which is reset before/just after the function returns.
2424+- Long-lived “subsystem” arena which is used to allocate return values for
2525+ the caller.
2626+- A permanent arena which is never freed.