code: def get_value(self, sid, dt, field):
          
          return self.frames[field].loc[dt, sid]
docs: 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.