digraph Perl
{
graph [ rankdir="TB" ]
node [ shape="oval" ]
edge [ color="white" ]

subgraph "cluster.1"
{
graph [ bgcolor="red" rankdir="TB" ]
node [ shape="oval" ]
edge [ color="white" ]

"node.1" [ color="green" shape="rect" ]
"node.2"
}
"node.1" -> "node.2" [ color="white" label="" ]
}
