| Of course, you can again inherit from a subclass, making this class the superclass of the new subclass. This leads to a hierarchy of superclass/subclass relationships.
| If you draw this hierarchy you get an inheritance graph.
| In the literature you also find illustrations where the arrowed lines are used just the other way around. The direction in which the arrowed line is used, depends on
| how the corresponding author has decided to understand it.
| In this tutorial the arrowed line is always directed towards the superclass.
| In the further discussion an unmarked arrowed line indicates “inherit-from''.