One-line dependency injection in ES6

subclass.js

/**
 * Dependency injection in ES6. Parentheses can be omitted for arrow functions with
 * only one argument, and by omitting the curly braces it automatically returns
 * the proceeding expression, in this case, the Subclass that extends from the
 * Superclass that is injected. So cool.
 */
export default Superclass => class Subclass extends Superclass { ... }