AthHIP::SingleStreamSvc Node1 AthHIP::SingleStreamSvc   + initialize() + stream() * initialize() * stream() Node2 extends< AthService, IStreamSvc >     Node2->Node1 Node3 std::unique_ptr< const AthHIP::Details::Stream >   + operator->() Node3->Node1 -m_stream Node4 AthHIP::Details::Stream - m_stream + Stream() + ~Stream() + stream() + name() Node4->Node3 +ptr