code: def test_putmask_td64(self):
      # GH#37968
      dti = date_range("2016-01-01", periods=9)
      tdi = dti - dti[0]
      idx = IntervalIndex.from_breaks(tdi)
      mask = np.zeros(idx.shape, dtype=bool)
      mask[0:3] = True
  
      result = idx.putmask(mask, idx[-1])
      expected = IntervalIndex([idx[-1]] * 3 + list(idx[3:]))
      tm.assert_index_equal(result, expected)
  
imports: import re
  import numpy
  import pytest
  from pandas.errors import InvalidIndexError
  from pandas import NA, CategoricalIndex, DatetimeIndex, Index, Interval, IntervalIndex, MultiIndex, NaT, Timedelta, Timestamp, array, date_range, interval_range, isna, period_range, timedelta_range
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestPutmask obj's underlying member method code with example usage: obj.test_putmask_td64() without return types