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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 delete(self, symbol, date_range=None):
 """ Delete all chunks for a symbol. Which are, for the moment, fully contained in the passed in date_range. Parameters symbol : `str` symbol name for the item date_range : `date.DateRange` DateRange to delete ticks in """

        query = {SYMBOL: symbol}
        date_range = to_pandas_closed_closed(date_range)
        if date_range is not None:
            assert date_range.start and date_range.end
            query[START] = {'$gte': date_range.start}
            query[END] = {'$lte': date_range.end}
        else:
            # delete metadata on complete deletion
            self._metadata.delete_one({SYMBOL: symbol})
        return self._collection.delete_many(query)