code: def test_preserved_frame(self):
      df = pd.DataFrame(
          {"A": [1, 2], "B": [3, 4]}, index=["a", "b"]
      ).set_flags(allows_duplicate_labels=False)
      assert df.loc[["a"]].flags.allows_duplicate_labels is False
      assert (
          df.loc[:, ["A", "B"]].flags.allows_duplicate_labels is False
      )
  
imports: import operator
  import numpy
  import pytest
  import pandas
  import pandas._testing
label_desc: Use image node_id 4 for calling the TestPreserves obj's underlying member method code with example usage: obj.test_preserved_frame() without return types