code: def test_mixed_index_at_iat_loc_iloc_series(self):
      # GH 19860
      s = Series([1, 2, 3, 4, 5], index=["a", "b", "c", 1, 2])
      for el, item in s.items():
          assert s.at[el] == s.loc[el] == item
      for i in range(len(s)):
          assert s.iat[i] == s.iloc[i] == i + 1
  
      with pytest.raises(KeyError, match="^4$"):
          s.at[4]
      with pytest.raises(KeyError, match="^4$"):
          s.loc[4]
  
imports: from datetime import datetime, timedelta
  import itertools
  import numpy
  import pytest
  from pandas import DataFrame, Index, Series, Timedelta, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 7 for calling the TestAtAndiAT obj's underlying member method code with example usage: obj.test_mixed_index_at_iat_loc_iloc_series() without return types