Copyfunction flatMap<T, U>( transform: (value: T, index: number) => Source<U>, ): Operator<T, U>1function flatMap<T, U>(2 transform: (value: T, index: number) => Source<U>,3): Operator<T, U>
function flatMap<T, U>( transform: (value: T, index: number) => Source<U>, ): Operator<T, U>1function flatMap<T, U>(2 transform: (value: T, index: number) => Source<U>,3): Operator<T, U>