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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 _spot_col(self, colname):
 """ Get the colname from daily_bar_table and read all of it into memory, caching the result. Parameters colname : string A name of a OHLCV carray in the daily_bar_table Returns ------- array (uint32) Full read array of the carray in the daily_bar_table with the given colname. """

        try:
            col = self._spot_cols[colname]
        except KeyError:
            col = self._spot_cols[colname] = self._table[colname]
        return col