code: def test_setitem_new_column_mixed_depth(self):
      arrays = [
          ["a", "top", "top", "routine1", "routine1", "routine2"],
          ["", "OD", "OD", "result1", "result2", "result1"],
          ["", "wx", "wy", "", "", ""],
      ]
  
      tuples = sorted(zip(*arrays))
      index = MultiIndex.from_tuples(tuples)
      df = DataFrame(
          np.random.default_rng(2).standard_normal((4, 6)),
          columns=index,
      )
  
      result = df.copy()
      expected = df.copy()
      result["b"] = [1, 2, 3, 4]
      expected["b", "", ""] = [1, 2, 3, 4]
      tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  from pandas.errors import SettingWithCopyError
  import pandas
  from pandas import DataFrame, MultiIndex, Series, date_range, isna, notna
  import pandas._testing
label_desc: Use image node_id 1 for calling the TestSetitemWithExpansionMultiIndex obj's underlying member method code with example usage: obj.test_setitem_new_column_mixed_depth() without return types