Create a new graph of type `graph-type'. Graph type can be a symbol naming a sub-class of basic-graph or a list. If it is a list of symbols naming different classes. If graph-type is a list, then a class which has all of the listed classes as superclasses will be found (or created). In either case, the new graph will be created as if with a call to make-instance.
| make-graph < LIST > |
| make-graph < SYMBOL > |