code: def _spot_col(self, colname):
          
          try:
              col = self._spot_cols[colname]
          except KeyError:
              col = self._spot_cols[colname] = self._table[colname]
          return col
docs: 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.