Classes extending the Flowable base reactive class and implementing
the Subscriber interface at the same time (aka hot Flowables).
||Processor that emits the very last value followed by a completion event or the received error
||Processor that emits the most recent item it has observed and all subsequent observed items to each subscribed
||Represents a Subscriber and a Flowable (Publisher) at the same time, allowing
multicasting events from a single source to multiple child Subscribers.
||Processor that multicasts all subsequently observed items to its current Subscribers.
||Replays events to Subscribers.
||Processor that allows only a single Subscriber to subscribe to it during its lifetime.