'Parameters
sid : int
The asset identifier.
day : datetime64-like
Midnight of the day for which data is requested.
field : 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):

    return self.panel.loc[(sid, dt, field)]
