Adding Child Pages to a Tabbed Page

Hi,
I've been trying to add child pages to a Tabbed page using the 2nd approach shown over here:
http://iosapi.xamarin.com/?link=T:Xamarin.Forms.TabbedPage

However I'm not able to do so as the Children collections is a read-only property. Refer screenshot.

Can someone clarify on this inconsistency. How am I supposed to add child pages to the tabbed page when its read only.

PS: In case its read only and there's some other way around, how could the sample demonstrate adding to the Children collections. Isn't the code tested before being posted in the online docs