Given the following Morris preorder traversal code, what is the final output list after running preorderTraversal on the tree below? Tree structure:

Given the following Morris preorder traversal code, what is the final output list after running preorderTraversal on the tree below? Tree structure:

    1
   / \
  2   3

def preorderTraversal(root):
    result = []
    current = root
    while current:
        if current.left is None:
            result.append(current.val)
            current = current.right
        else:
            predecessor = current.left
            while predecessor.right and predecessor.right != current:
                predecessor = predecessor.right
            if predecessor.right is None:
                predecessor.right = current
                result.append(current.val)
                current = current.left
            else:
                predecessor.right = None
                current = current.right
    return result