code: def test_root():
      """Test root access from leaf"""
      child = TreeNode("test")
      parent = TreeNode("test", children=[child])
      grand_parent = TreeNode("test", children=[parent])
  
      assert child.root is grand_parent
      assert child.root is parent.root
      assert grand_parent.root is grand_parent
  
imports: from orion.core.utils.tree import DepthFirstTraversal, PreOrderTraversal, TreeNode, flattened
label_desc: Use image node_id 15 for calling a global function with example usage: test_root() without return types