Part 4
======

## Installation

```bash
elm-package install
```

(Answer `y` at the prompt. In rare cases a known issue can cause the download
to fail; in that case, just run `elm-package install` again.)

## Building

```bash
elm-live Main.elm --open --output=elm.js
```

## References

* [Union Types syntax reference](http://elm-lang.org/docs/syntax#union-types)