Identify and extract next page url

Get the xpath for the URL of the next page in the current list of biographies, convert it to a valid wikipedia URL.
It'll actually be an array - there are 7 start pages altogether, for different quality categories. Wikipedia throttles attempts to grab too many pages, so I'm doing the basic development using just one, for now, instead of iterating through all of them. I don't want to cause wikipedia to throttle or block my ip address.  :-)   When it's done, it'll only have to do a single iteration through all of the pages and store the result. For now, though, when I'm repeating the search every time I make a change and test it, it's safest to just use one page with little content, so I don't create any discernible server load.