code: def test_get_dummies_dont_sparsify_all_columns(self, sparse):
      # GH18914
      df = DataFrame.from_dict({"GDP": [1, 2], "Nation": ["AB", "CD"]})
      df = get_dummies(df, columns=["Nation"], sparse=sparse)
      df2 = df.reindex(columns=["GDP"])
  
      tm.assert_frame_equal(df[["GDP"]], df2)
  
imports: import re
  import unicodedata
  import numpy
  import pytest
  import pandas.util._test_decorators
  from pandas.core.dtypes.common import is_integer_dtype
  import pandas
  from pandas import ArrowDtype, Categorical, CategoricalDtype, CategoricalIndex, DataFrame, Index, RangeIndex, Series, SparseDtype, get_dummies
  import pandas._testing
  from pandas.core.arrays.sparse import SparseArray
label_desc: Use image node_id 33 for calling the TestGetDummies obj's underlying member method code with example usage: obj.test_get_dummies_dont_sparsify_all_columns(sparse) without return types