code: def prune_tour_worker(arg):
      
      from .chic import score_evaluate_M
  
      t, stour, tour_score, active_sizes, M = arg
      stour_score, = score_evaluate_M(stour, active_sizes, M)
      delta_score = tour_score - stour_score
      log10d = np.log10(delta_score) if delta_score > 1e-9 else -9
      return t, log10d
docs: Worker thread for CLMFile.prune_tour()