Extends the Stream class with the ability to convert the source Stream into a new Stream each time the source emits an item.
S>( Stream< S>mapper(T value)) → Stream< S>
- Converts each emitted item into a Stream using the given mapper function. The newly created Stream will be be listened to and begin emitting items downstream. [...]
S>( Stream< Iterable<mapper(T value)) → Stream< S>> S>
- Converts each item into a Stream. The Stream must return an Iterable. Then, each item from the Iterable will be emitted one by one. [...]