Understanding the stateful preorder pattern

Preorder traversal follows the node-left-right processing sequence, where we process a node as we enter it and repeat the process recursively for both its left and right subtree. Because a node is processed before its left and right subtrees, the preorder traversal is ideal for solving problems where data must be processed and passed down from parent to child nodes. The child nodes then process the data they receive from their parent and pass it down to their children.