code: def test_get_true_ancestor_no_parent(self):
      lineage = LineageNode(1)
      assert lineage.get_true_ancestor() is None
  
imports: import os
  import random
  import pytest
  from base import ObjectiveStub, TrialStub, build_full_tree, build_population, compare_generations
  from orion.algo.pbt.pbt import LineageNode, Lineages
label_desc: Use image node_id 6 for calling the TestLineageNode obj's underlying member method code with example usage: obj.test_get_true_ancestor_no_parent() without return types