This crate provides utilities for implementing inverted indexes
```rust
use invertedindexutil::entitylist::insertentitymut;
let mut entitylist: Vec
insert_entity_mut(&mut entity_list, b"aaaaaaaaaaaaaaaa");
insert_entity_mut(&mut entity_list, b"cccccccccccccccc");
insert_entity_mut(&mut entity_list, b"aaaaaaaaaaaaaaaa");
insert_entity_mut(&mut entity_list, b"bbbbbbbbbbbbbbbb");
assert_eq!(
&entity_list[..],
&b"aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbcccccccccccccccc"[..]
);
```