a, group [collapsed=yes] {
    b, c, d;
}, e;
a->b: Message;
box b--d: Box {
    b->c->d: Message;
};
d->e: Message;
d<-e: Message \#2;
box group--group: Box {
    b<-c-d: Message \#2;
};
a<-b: Message \#2;
