new file mode 100644

@@ -0,0 +1,15 @@

+graph G {

+  e

+  subgraph clusterA {

+    a -- b;

+    subgraph clusterC {

+      C -- D;

+    }

+  }

+  subgraph clusterB {

+    d -- f

+  }

+  d -- D

+  e -- clusterB

+  clusterC -- clusterB

+}