'Retrieve the value at the given coordinates.
Parameters
sid : int
The asset identifier.
dt : pd.Timestamp
The timestamp for the desired data point.
field : string
The OHLVC name for the desired data point.
Returns
value : float|int
The value at the given coordinates, ``float`` for OHLC, ``int``
for \'volume\'.
Raises
NoDataOnDate
If the given dt is not a valid market minute (in minute mode) or
session (in daily mode) according to this reader\'s tradingcalendar.'

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

    pass
