code: def test_linked_list():
      linked_list = gridsearch.LinkedList()
      linked_list.insert("0")
      assert linked_list.next("0") is None
      linked_list.insert("1")
      assert linked_list.next("0") == "1"
      assert linked_list.next("1") is None
      linked_list.insert("2", "0")
      assert linked_list.next("0") == "2"
      assert linked_list.next("2") == "1"
      assert linked_list.next("1") is None
      linked_list.insert("3", "1")
      linked_list.insert("4")
      assert linked_list.next("0") == "2"
      assert linked_list.next("2") == "1"
      assert linked_list.next("1") == "3"
      assert linked_list.next("3") == "4"
      assert linked_list.next("4") is None
  
file_path: keras-tuner/keras_tuner/tuners/gridsearch_test.py
imports: import random
  from keras_tuner.backend import keras
  from keras_tuner.engine import hypermodel
  from keras_tuner.engine import trial
  from keras_tuner.tuners import gridsearch
label_desc: Use image node_id 7 for calling a global function with example usage: test_linked_list() without return types