Code Fragment: InspectableBinaryTree

template <typename Object>
class InspectableBinaryTree
  : public InspectableTree<Object> {
public:
  Position leftChild(const Position& v) const;		// left child of v
  Position rightChild(const Position& v) const;		// right child of v
  Position sibling(const Position& v) const;		// sibling of v
};