code: def test_get_trials_at_depth_given_non_existing_trial(self):
      lineages = Lineages()
  
      with pytest.raises(KeyError, match="idontexist"):
          lineages.get_trials_at_depth(TrialStub(id="idontexist"))
  
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 19 for calling the TestLineages obj's underlying member method code with example usage: obj.test_get_trials_at_depth_given_non_existing_trial() without return types