input: Write a python function to compare two lists and return elements not in the other list.
  assert compare_lists([1, 2, 3, 4], [3, 4, 5, 6]) == ([1, 2], [5, 6])
  assert compare_lists(['apple', 'banana', 'cherry'], ['banana', 'cherry', 'date']) == (['apple'], ['date'])
  assert compare_lists([10, 20, 30], [40, 50, 60]) == ([10, 20, 30], [40, 50, 60])
output: def compare_lists(list1, list2):
      not_in_list2 = [item for item in list1 if item not in list2]
      not_in_list1 = [item for item in list2 if item not in list1]
      return not_in_list2, not_in_list1