code: def test_index_unique(self):
      idx = PeriodIndex([2000, 2007, 2007, 2009, 2009], freq="Y-JUN")
      expected = PeriodIndex([2000, 2007, 2009], freq="Y-JUN")
      tm.assert_index_equal(idx.unique(), expected)
      assert idx.nunique() == 3
  
file_path: pandas/pandas/tests/indexes/period/test_period.py
imports: import numpy
  import pytest
  from pandas import Index, NaT, Period, PeriodIndex, Series, date_range, offsets, period_range
  import pandas._testing
label_desc: Use image node_id 5 for calling the TestPeriodIndex obj's underlying member method code with example usage: obj.test_index_unique() without return types