code: def test_positive(maxk=14):
      print("positive test")
  
      for k in range(2, maxk + 1):
          start_time = time.time()
          trial = 0
          for t in nx.nonisomorphic_trees(k):
              positive_single_tree(t)
              trial += 1
          print(k, trial, time.time() - start_time)
  
file_path: networkx/networkx/algorithms/isomorphism/tests/test_tree_isomorphism.py
imports: import random
  import time
  import pytest
  import networkx
  from networkx.algorithms.isomorphism.tree_isomorphism import rooted_tree_isomorphism, tree_isomorphism
  from networkx.classes.function import is_directed
label_desc: Use image node_id 6 for calling a global function with example usage: test_positive(maxk) without return types