Continuation<TResult, TContinuationResult>	A function that is called to continue execution after completion of a `Task`.
OnCanceledListener	Listener called when a `Task` is canceled.
OnCompleteListener<TResult>	Listener called when a `Task` completes.
OnFailureListener	Listener called when a `Task` fails with an exception.
OnSuccessListener<TResult>	Listener called when a `Task` completes successfully.
OnTokenCanceledListener	Listener called when a `CancellationToken` is canceled successfully.
SuccessContinuation<TResult, TContinuationResult>	A function that is called to continue execution then a `Task` succeeds.

CancellationToken	Propagates notification that operations should be canceled.
CancellationTokenSource	Creates a new `CancellationToken` or cancels one that has already created.
Task<TResult>	Represents an asynchronous operation.
TaskCompletionSource<TResult>	Provides the ability to create `Task`-based APIs.
TaskExecutors	Standard `Executor` instances for use with `Task`.
Tasks	`Task` utility methods.

RuntimeExecutionException Runtime version of ExecutionException.