Inheritance Hierarchy

There is no (technical) limit to how deeply we can nest an inheritance tree. For example:

Tiger inherits from Feline inherits from Animal inherits from LivingThing.

That said, be careful! New programmers often get carried away. You should never think to yourself:

"Well most wizards are elves... so I'll just have Wizard inherit from Elf"

A good child class is a strict subset of its parent class.

Assignment

Let's add a new game unit: Crossbowman. A crossbowman is always an archer, but not all archers are crossbowmen. Crossbowmen have several arrows, but they have an additional method: triple_shot().

Complete the use_arrows method on the Archer class. It should remove num arrows, but if there aren't enough arrows to remove, it should raise a not enough arrows exception instead.
Complete the Crossbowman class.
- Its constructor should call its parent's constructor.
- Its triple_shot method should:
  - Use 3 arrows
  - Return the string TARGET was shot by 3 crossbow bolts where TARGET is the name of the Human that was shot (any Human can be a target).