<PackageReference Include="System.Reactive" Version="4.1.2" />

SchedulerOperation

public sealed class SchedulerOperation
Represents an awaitable scheduler operation. Awaiting the object causes the continuation to be posted back to the originating scheduler's work queue.
public SchedulerOperation ConfigureAwait(bool continueOnCapturedContext)

Controls whether the continuation is run on the originating synchronization context (false by default).

Gets an awaiter for the scheduler operation, used to post back the continuation.