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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 pop(self, symbol):
 """ Delete current metadata of `symbol` Parameters symbol : `str` symbol name to delete Returns ------- Deleted metadata """

        last_metadata = self.find_one({'symbol': symbol}, sort=[('start_time', pymongo.DESCENDING)])
        if last_metadata is None:
            raise NoDataFoundException('No metadata found for symbol {}'.format(symbol))

        self.find_one_and_delete({'symbol': symbol}, sort=[('start_time', pymongo.DESCENDING)])
        mongo_retry(self.find_one_and_update)({'symbol': symbol}, {'$unset': {'end_time': ''}},
                                              sort=[('start_time', pymongo.DESCENDING)])

        return last_metadata