code: def test_insert_tree():
      # initialize root node and add 1 new node, check it goes as root's child and has it's parent as root
      _, dist_func = initialize_for_bktree()
      hash_dict = {"a": "9", "b": "D"}
      bk = BKTree(hash_dict, dist_func)
      assert bk.ROOT == "a"
      assert "b" in list(bk.dict_all["a"].children.keys())
      assert bk.dict_all["b"].parent_name == "a"
  
file_path: imagededup/tests/test_bktree.py
imports: from collections import OrderedDict
  from imagededup.methods.hashing import Hashing
  from imagededup.handlers.search.bktree import BKTree, BkTreeNode
label_desc: Use image node_id 3 for calling a global function with example usage: test_insert_tree() without return types