cancel method
Communicates a request for cancellation.
The associated CancellationToken will be notified of the cancellation and will transition to state where isCancellationRequested returns true. Any callbacks of cancelable operations registered with the CancellationToken will be executed.
Implementation
void cancel([bool throwOnFirstException = false]) {
_throwIfDisposed();
_notifyCancellation(throwOnFirstException);
}