code: def test_basic(self) -> None:
      d = Document()
      dm = bdm.DocumentModelManager(d)
      assert len(dm) == 0
  
      # module manager should only hold a weak ref
      assert len(gc.get_referrers(d)) == 0
  
imports: from __future__ import annotations
  import pytest
  import gc
  from unittest.mock import MagicMock, patch
  from bokeh.core.has_props import Local
  from bokeh.core.properties import Instance, Nullable
  from bokeh.core.types import ID
  from bokeh.document import Document
  from bokeh.model import Model
  from bokeh.models import Div, Row
  import bokeh.document.models
label_desc: Use image node_id 1 for calling the TestDocumentModelManager obj's underlying member method code with example usage: obj.test_basic() without return types