This is the last thing I have questions about. The purpose of the pg_hit_set_info_t seems a bit muddled to me and I'm having trouble placing it logically.
```size``` is a duplicate of information in the HitSet; just for indexing purposes?
```target_size``` is used when the PG is doing insertions to decide if the HitSet is full, but not elsewhere, and we should just be asking the HitSet "are you full?" instead of referring to an external data structure.
```begin, end``` are I guess for indexing/lookup purposes, but not used yet?
```version``` is for deleting them.