Copyfunction defaultIfEmptyTo<T>(value: T): <U>(source: Source<U>) => Source<T | U>1function defaultIfEmptyTo<T>(value: T): <U>(source: Source<U>) => Source<T | U>
function defaultIfEmptyTo<T>(value: T): <U>(source: Source<U>) => Source<T | U>1function defaultIfEmptyTo<T>(value: T): <U>(source: Source<U>) => Source<T | U>