code: def test_utils_namespace():
      """Ensure objects are not unintentionally exposed in utils namespace."""
      with pytest.raises(ImportError):
          from networkx.utils import nx
      with pytest.raises(ImportError):
          from networkx.utils import sys
      with pytest.raises(ImportError):
          from networkx.utils import defaultdict, deque
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_utils_namespace() without return types