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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _maybe_cast_slice_bound(self, label, side, kind):
 """Adapted from pandas.tseries.index.DatetimeIndex._maybe_cast_slice_bound"""

        if isinstance(label, str):
            parsed, resolution = _parse_iso8601_with_reso(self.date_type,
                                                          label)
            start, end = _parsed_string_to_bounds(self.date_type, resolution,
                                                  parsed)
            if self.is_monotonic_decreasing and len(self) > 1:
                return end if side == 'left' else start
            return start if side == 'left' else end
        else:
            return label