code: def test_empty_ds():
      ds = Docstring(None)
      ds.replace_block("summary", ["The is the new summary."])
  
      ds.remove_parameters("x")
  
      new = Parameter("w", "ndarray", ["An array input."])
      ds.insert_parameters("y", new)
      assert str(ds) == "None"
  
file_path: statsmodels/statsmodels/tools/tests/test_docstring.py
imports: import pytest
  from statsmodels.tools.docstring import Docstring, remove_parameters, Parameter
label_desc: Use image node_id 7 for calling a global function with example usage: test_empty_ds() without return types