The close() Function
The close() function stores the final result of an operation into the IOU object. It releases any threads that have been waiting for the result.
RWTIOUEscrow also has a function operator called operator()() and an assignment operator called operator=() that have the same capability as the close() function. Given that “iou” is an instance of the RWTIOUEscrow class, the following statements are functionally identical:
iou.close(value);
iou(value);
iou = value;
