code: def test_get_best_trial_empty(self):
      trial = TrialStub(id="id-1", objective=1)
      lineage = LineageNode(trial)
      assert lineage.get_best_trial().id == "id-1"
  
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 9 for calling the TestLineageNode obj's underlying member method code with example usage: obj.test_get_best_trial_empty() without return types