Specifies if cancellation has been requested. This value should never be set explicitly. Instead, a CancellationToken should be cancelled using the CancellationTokenSource that it was derived from.
Register a handler to be notified when cancellation occurs.
A cancellation token allows you to check if an operation has been cancelled. Additionally, you can subscribe to be notified when cancellation occurs. CancellationTokens should only be obtained from the CancellationTokenSource.token property.