/// <summary>
/// To create a Reactive Extension for the order book change event.
/// </summary>
/// <param name="marketDepth">The order book to be traced for change event.</param>
/// <returns>Reactive Extension.</returns>
public static IObservable <MarketDepth> RxWhenDepthChanged(this MarketDepth marketDepth)
{
return(marketDepth.RxDepthChanged());
}