code: def test_insert_tree_collision():
      # initialize root node, add 1 new node and enter another node with same distance from root, check it goes not as
      # root's child but the other node's child
      _, dist_func = initialize_for_bktree()
      hash_dict = OrderedDict(
          {"a": "9", "b": "D", "c": "8"}
      )  # to guarantee that 'a' is the root of the tree
      bk = BKTree(hash_dict, dist_func)
      assert bk.ROOT == "a"
      assert len(bk.dict_all[bk.ROOT].children) == 1
      assert "c" in list(bk.dict_all["b"].children.keys())
  
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 4 for calling a global function with example usage: test_insert_tree_collision() without return types