export default function findIndex<T>(iterable: Iterable<T>): number | undefined;
export default function findIndex<T>(iterable: Iterable<T>, predicate: ((value: T, index: number) => any)): number | undefined;
export default function findIndex<T, Default>(iterable: Iterable<T>, defaultValue: Default, predicate: ((value: T, index: number) => any)): Default | number;