[CharlieDigital]

`OneOrMore<T>` was an example of using `union` types.

You are free to call it `public union Some<T>(T, IEnumerable<T>)`

[gf000]

But now you can only call methods that are available for both T and IEnumerable<T>, you have no way of knowing which it actually is. (You would know if it were sum types)