/// <summary>
 /// Builds a welcome dialog, shown on conversation start
 /// </summary>
 /// <param name="dialogs">the dialog collection</param>
 /// <param name="factory">the factory used to create dialogs</param>
 /// <param name="dialogName">the name of the dialog</param>
 /// <param name="nextStep">the next step to go to in the chain</param>
 /// <returns>
 /// The <see cref="DialogSet"/>.
 /// </returns>
 public static DialogSet WithWelcome(
     this DialogSet dialogs,
     IDialogFactory <DialogSet> factory,
     string dialogName,
     IDialogStep nextStep)
 {
     return(factory.BuildWelcomeDialog(dialogs, dialogName, nextStep));
 }