code: def test_maybe_cast_slice_duplicate_monotonic(self):
      # https://github.com/pandas-dev/pandas/issues/16515
      idx = DatetimeIndex(["2017", "2017"])
      result = idx._maybe_cast_slice_bound("2017-01-01", "left")
      expected = Timestamp("2017-01-01")
      assert result == expected
  
imports: from datetime import date, datetime, time, timedelta
  import numpy
  import pytest
  from pandas._libs import index
  from pandas.compat.numpy import np_long
  import pandas
  from pandas import DatetimeIndex, Index, Timestamp, bdate_range, date_range, notna
  import pandas._testing
  from pandas.tseries.frequencies import to_offset
label_desc: Use image node_id 2 for calling the TestMaybeCastSliceBound obj's underlying member method code with example usage: obj.test_maybe_cast_slice_duplicate_monotonic() without return types