We have a working TreeNode class, but there’s no time to enjoy a refreshing glass of lemonade. Trees are all about data hierarchy, and we need a parent-child relationship to make that work.
To review: child nodes are held as references by another instance of TreeNode, known as the parent node.
We’ll store the references to child nodes in a Python list and define an add_child method on our TreeNode class which will add nodes to that list.
Instructions
Modify our __init__() method by setting self.children to be an empty list.
Define add_child on the TreeNode class. It should take self and child_node as parameters. In the body of add_child, start with print("Adding " + child_node.value).
After the print statement, use a list method to add the child_node to self.children.
Finally, call add_child on root and pass child as an argument.