code: def test_unique_level(self, index_flat):
      # don't test a MultiIndex here (as its tested separated)
      index = index_flat
  
      # GH 17896
      expected = index.drop_duplicates()
      for level in [0, index.name, None]:
          result = index.unique(level=level)
          tm.assert_index_equal(result, expected)
  
      msg = "Too many levels: Index has only 1 level, not 4"
      with pytest.raises(IndexError, match=msg):
          index.unique(level=3)
  
      msg = (
          rf"Requested level \(wrong\) does not match index name "
          rf"\({re.escape(index.name.__repr__())}\)"
      )
      with pytest.raises(KeyError, match=msg):
          index.unique(level="wrong")
  
imports: from copy import copy, deepcopy
  import re
  import numpy
  import pytest
  from pandas.compat import IS64
  from pandas.compat.numpy import np_version_gte1p25
  from pandas.core.dtypes.common import is_integer_dtype, is_numeric_dtype
  import pandas
  from pandas import CategoricalIndex, MultiIndex, PeriodIndex, RangeIndex
  import pandas._testing
label_desc: Use image node_id 11 for calling the TestCommon obj's underlying member method code with example usage: obj.test_unique_level(index_flat) without return types