code: def test_docstrings():
      # test that docstring insertions worked for all Visual+Node subclasses
      for name in dir(visuals):
          obj = getattr(visuals, name)
          if isinstance(obj, type) and issubclass(obj, Node):
              if obj is Node or obj is VisualNode:
                  continue
              assert "This class inherits from visuals." in obj.__doc__
              assert "parent : Node" in obj.__doc__
  
file_path: vispy/vispy/scene/tests/test_visuals.py
imports: import pytest
  from vispy.scene import visuals, Node
  from vispy.scene.visuals import VisualNode
  import vispy.visuals
label_desc: Use image node_id 1 for calling a global function with example usage: test_docstrings() without return types