Flatten Binary Tree to Linked List

main.py

class Solution:
    def flatten(self, root: TreeNode) -> None:
        # If current node is null, or it's a leaf, we don't do shit.
        if root is None or (root.left is None and root.right is None):
            return
        if root.left:
            self.flatten(root.left)
            original_right = root.right
            root.right = root.left
            root.left = None
            rightmost_node = root.right
            while rightmost_node.right:
                rightmost_node = rightmost_node.right
            rightmost_node.right = original_right
        if root.right:
            self.flatten(root.right)

https://www.youtube.com/watch?v=598gdjE6Quo