Module of the day is: GraphViz::ISA::Multi because I needed to get a simple overview of some related classes in order to determine the impact of my change (and where to apply the change).
Also immediately obvious from this high-level view is that there should be a general base class in the middle of the inheritance tree to provide a new set of behaviour. The general behaviour is already there, but without a proper level of abstraction it sits there mixed up with some very specific behaviour. Not very clear.
