Hash-indexed collection
==============
You could call this a cache, or a kind of set. It is a simple wrapper around
`HashSet` to allow values of type `T` to be stored in a set indexed by some
type `K`, where values of type `K` can be somehow "extracted" from those of
type `T`.
Check documentation on type `HashIndexed` for usage.
## License
Licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
at your option.
### Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any
additional terms or conditions.