public function whenMemberLeftCommittee(MemberLeftCommittee $event)
 {
     $committee = $this->committees->find((string) $event->committeeId());
     $committee = $committee->removeMember($event->memberId());
     $this->committees->save($committee);
 }
 protected function applyMemberLeftCommittee(MemberLeftCommittee $event)
 {
     unset($this->members[array_search($event->memberId(), $this->members)]);
 }