code: def _add_delta_tdi(self, other):
          
          if len(self) != len(other):
              raise ValueError("cannot add indices of unequal length")
  
          if isinstance(other, np.ndarray):
              # ndarray[timedelta64]; wrap in TimedeltaIndex for op
              from pandas import TimedeltaIndex
              other = TimedeltaIndex(other)
  
          self_i8 = self.asi8
          other_i8 = other.asi8
          new_values = checked_add_with_arr(self_i8, other_i8,
                                            arr_mask=self._isnan,
                                            b_mask=other._isnan)
          if self._hasnans or other._hasnans:
              mask = (self._isnan) | (other._isnan)
              new_values[mask] = iNaT
          return new_values.view('i8')
docs: Add a delta of a TimedeltaIndex
          return the i8 result view