Goal: The Block, Element, Modifier methodology (BEM) is a popular naming convention for classes in CSS. For example, the block component would be represented as `btn`, element that depends upon the block would be represented as `btn__price`, modifier that changes the style of the block would be represented as `btn--big` or `btn__price--warning`. Implement `BEM<B, E, M>` which generates a string union from these three parameters. Where `B` is a string literal, `E` and `M` are string arrays (can be empty). Source challenge: https://github.com/type-challenges/type-challenges/tree/main/questions/03326-medium-bem-style-string Reference explanation: https://github.com/ghaiklor/type-challenges-solutions/blob/main/en/medium-bem-style-string.md