digraph {
  packmode=array_i1

  subgraph cluster_a {
    label="Cluster A";
    packmode=array_i7

    1; 3; 5; 7; 9; 11; 13; 
  }
  subgraph cluster_b {
    label="Cluster B";
    packmode=array_i4
    2; 4; 6; 8; 
  }
}
