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

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)