WrappedTask

Code that gets called after the task gets started - it may spawn other tasks instead of calling leaf.

Start task.

Wait for task to finish.

Try to cancel the task.

If the task has been cancelled successfully, those syncing on it may automatically be notified, depending on the implementation. If they aren't, this release method should be called after processing the cancelled task.

This method may be overridden.

the body of this task - what it executes, how it gets split and how results are merged.