Is it guaranteed that len() will be above all interned symbol's to_usize() for contiguous backends?

[jingyu9575]

Hi, thank you for the library.

I'm trying to use a Symbol->T map and want to simplify to a Vec with index. Currently I'm tracking all get_or_intern() results for the maximum value, and calculate the Vec size. Is it possible to use a contiguous backend (StringBackend/BucketBackend) and len() instead?