Extend the BinaryTreeClass to implement the Iterable interface by providing an iterator. The iterator should access the tree elements using an inorder traversal. The iterator is implemented as a nested private class. (Note: unlike Node, this class should not be static.)

Design hints:

You will need a stack to hold the path from the current node back to the root. You will also need a reference to the current node (current) and a variable that stores the last item returned.

To initialize current, the constuctor should start at the root and follow the left links untill a node is reached that does not have a left child. This node is the initial current node.

The remove method can throw an UnsupportedOperationException. The next method should use the following algorithm:

1. Save the contents of the current node. 2. IF the curent node has a right child 3. push the current node onto the stack 4. set the currrent node to the right child 5. while the current node has aleft child. 6. push the current node into the stack 7. set the current node to the left child 8. Else the current node does not have a right child 9. while the stack is not empty and the top node of the stacks right child is equal to the current node 10. set the current node to the top of the stack and pop the stack 11. IF the stack is empty 12. set the current node to null indicating the iteration is complete 13. ELSE 14. set the current node to the top of the stack and pop the stack 15. return the saved contents of the initial current node.