'digraph Perl {
 graph [ label="Demo of 3 subgraphs (2 being clusters), and 1 frame" rankdir="TB" ]
 node [ shape="oval" ]
 edge [ color="grey" penwidth="3" ]
 "One" [ color="red" shape="circle" ]
 "Two" [ color="green" shape="doublecircle" ]
 "One" -> "Two" [ color="maroon" ]

 subgraph "cluster First subgraph" {
  graph [ label="Child the First" ]
  node [ color="magenta" shape="diamond" ]
  pencolor="white" 
  "Three"
  "Four" [ color="orange" shape="rectangle" ]
  "Three" -> "Four"
 }

 subgraph "cluster Second subgraph" {
  graph [ label="Child the Second" ]
  node [ color="magenta" shape="diamond" ]
  pencolor="purple" 
  "Five" [ color="blue" ]
  "Six" [ color="orange" shape="rectangle" ]
  "Five" -> "Six"
 }

 subgraph "Third subgraph" {
  graph [ label="Child the Third" ]
  node [ color="magenta" shape="diamond" ]
  "Seven" [ color="blue" shape="doubleoctagon" ]
  "Eight" [ color="orange" shape="rectangle" ]
  "Seven" -> "Eight"
 }
}
'
