Toolkit to produce and manipulate various types CFG graphs. The CFG graphs can have as nodes any implementation of Directed; typically, Unit elements or Block elements. The latter corresponds to BasicBlocks of Units. Some of the classes produce UnitGraphs where the control flow for exceptions is taken into account, while others produce graphs abstracting away extra exception-related edges. All classes in this package should now be thread safe. (Thu Feb 10 00:03:48 EST 2000)