Many To Many

This is a very simple crate which you can use for creating many-to-many data structures in Rust, it's intended purpose or use case is for situations where you need to map a set of ids to another set of ids (for example in PubSub, such as hive_pubsub which is what this crate was designed for). It does this by using two HashMaps, one linking Left to a set of Right and vice-versa.

This crate is like a fusion of bimap and multimap. I didn't see anything like this on crates.io, or anywhere really so I made my own thing.

Keys on either side (left or right) must implement Hash, Eq and Clone. See documentation for more information.

Example

```rust use manytomany::ManyToMany;

let mut map = ManyToMany::new(); map.insert(1, 2); map.insert(1, 3); map.insert(1, 4);

dbg!(map.get_left(&1));

map.insert(5, 2); map.remove(&1, &4);

dbg!(map.getleft(&1)); dbg!(map.getright(&2));

map.remove(&1, &2); map.remove(&1, &3);

asserteq!(map.getleft(&1), None); ```