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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 set_date_range(self, start=None, end=None):
 """ Update date range of stats, charts, etc. If None then the original date range is used. So to reset to the original range, just call with no args. Args: * start (date):
 start date * end (end):
 end date """

        start = self._start if start is None else pd.to_datetime(start)
        end = self._end if end is None else pd.to_datetime(end)
        self._update(self._prices.loc[start:end])