Navigates back to the previous page by popping the current page from the navigation stack. Also closes a modal window.
Will not work if called from the root page, i.e. when there is just the single default page in the navigation stack.
If the optional Number of pages value is more than the current number of pages in the navigation stack, the user will be navigated back to the root page.
Number of pages
Go back more than one page.
Number of outputs: undefined
No output arguments.