digraph {
  // rankdir=LR;
  subgraph cluster_comp0{
    a->b;
    e->a;
    b->e;
  }
  subgraph cluster_comp1{
    f->g;
    g->f;
  }
  subgraph cluster_comp2{
    c->d;
    d->c;
    d->h;
    h->d;
  }
  b->c;
  e->f;
  c->g;
  h->g;
}