I think the last sample needs a `fba.reset()` call in between requests.

BTW, I used zig a lot recently and the opaque allocator system is great. You can create weird wrappers and stuff.

For example, the standard library json parser will parse json, deserialize a type that you requested (say, a struct). But it needs to allocate stuff. So it creates an arena for that specific operation and returns a wrapper that has a `deinit` method. Calling it deinits the arena so you essentially free everything in your graph of structs, arrays etc. And since it receives an upstream allocator for the arena, you could pass in any allocator. A fixed stack allocator if you wish to use stack space, another arena, maybe jemalloc wrapper. A test allocator that checks for memory leaks.. Whatever.