code: def test_partial_garbage_collect_does_not_clear_tree(self):
      obj = HoloMap(
          {0: ExampleElement([]), 1: ExampleElement([])}
      ).opts(style_opt1="A")
      obj.pop(0)
      gc.collect()
      custom_options = Store._custom_options["backend_1"]
      self.assertIn(obj.last.id, custom_options)
      self.assertEqual(len(custom_options), 1)
      obj.pop(1)
      gc.collect()
      self.assertEqual(len(custom_options), 0)
  
imports: import gc
  from holoviews.core.element import Element
  from holoviews.core.options import Keywords, Options, OptionTree, Store
  from holoviews.core.spaces import HoloMap
  from ..utils import LoggingComparisonTestCase
label_desc: Use image node_id 5 for calling the TestOptionsCleanup obj's underlying member method code with example usage: obj.test_partial_garbage_collect_does_not_clear_tree() without return types