code: def test_fork_non_existing_trial(self):
      lineages = Lineages()
      trial = TrialStub(id="stub")
      new_trial = TrialStub(id="fork")
  
      with pytest.raises(KeyError):
          new_lineage = lineages.fork(trial, new_trial)
  
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 4 for calling the TestLineages obj's underlying member method code with example usage: obj.test_fork_non_existing_trial() without return types