goBack
Calling this function will pop the back stack of the ScreenManager. If there are no screens on the backstack, it will safely return false. If you are using the ScreenManager and the goBack operation results in an unknown backstack, this will throw an IllegalStateException.
When this function returns true, all screenEvent observers will be notified of an MapboxScreenOperation.GO_BACK event. This operation requires an instance of the MapboxScreenManager in order to verify the back-stack.