'Parameters
sid : int
The asset identifier.
day : datetime64-like
Midnight of the day for which data is requested.
colname : string
The price field. e.g. (\'open\', \'high\', \'low\', \'close\', \'volume\')
Returns
float
The spot price for colname of the given sid on the given day.
Raises a NoDataOnDate exception if the given day and sid is before
or after the date range of the equity.
Returns -1 if the day is within the date range, but the price is
0.'

def get_value(self, sid, dt, field):

    ix = self.sid_day_index(sid, dt)
    price = self._spot_col(field)[ix]
    if (field != 'volume'):
        if (price == 0):
            return nan
        else:
            return (price * 0.001)
    else:
        return price
