A, B, C, D;
A->C: First segment;
join C->B: Tunneled [line.type=triple];
join B->D: Last Segment;

C->B: First;
join B->B: Second [side=left];
join B->A: Third;

A->B: Segment \#1;
join block ->: Segment \#2 [color=lgray];
join C->D->;

A->: Girl kiss;
join box B--B: Happy Boy;
join <-C: Girl kiss;

A->: Trigger;
join box B--B: State change;
join ->;
join box C--C: State change;
join ->: Message;
