code: def test_get_loc_na(self):
      idx = Index([np.nan, 1, 2], dtype=np.float64)
      assert idx.get_loc(1) == 1
      assert idx.get_loc(np.nan) == 0
  
      idx = Index([np.nan, 1, np.nan], dtype=np.float64)
      assert idx.get_loc(1) == 1
  
      # representable by slice [0:2:2]
      msg = "'Cannot get left slice bound for non-unique label: nan'"
      with pytest.raises(KeyError, match=msg):
          idx.slice_locs(np.nan)
      # not representable by slice
      idx = Index([np.nan, 1, np.nan, np.nan], dtype=np.float64)
      assert idx.get_loc(1) == 1
      msg = "'Cannot get left slice bound for non-unique label: nan"
      with pytest.raises(KeyError, match=msg):
          idx.slice_locs(np.nan)
  
imports: import numpy
  import pytest
  from pandas.errors import InvalidIndexError
  from pandas import NA, Index, RangeIndex, Series, Timestamp
  import pandas._testing
  from pandas.core.arrays import ArrowExtensionArray, FloatingArray
label_desc: Use image node_id 4 for calling the TestGetLoc obj's underlying member method code with example usage: obj.test_get_loc_na() without return types