/**
  * @param ServesEventStreamData $eventEnvelope
  */
 public function update(ServesEventStreamData $eventEnvelope)
 {
     echo get_class($eventEnvelope->getPayload()) . " with ID {$eventEnvelope->getStreamId()} was globally observed.\n";
 }
 /**
  * @param ServesEventStreamData $eventEnvelope
  *
  * @return IdentifiesEventStream
  */
 private function getStreamIdentifierForEventEnvelope(ServesEventStreamData $eventEnvelope)
 {
     return new EventStreamIdentifier($eventEnvelope->getStreamId());
 }