code: def test_holder():
      holder = Holder()
      holder.new_attr = 1
      assert hasattr(holder, "new_attr")
      assert getattr(holder, "new_attr") == 1
  
imports: import pytest
  import numpy
  from statsmodels.tools.testing import ParamsTableTestBunch, MarginTableTestBunch, Holder
label_desc: Use image node_id 3 for calling a global function with example usage: test_holder() without return types