UHD replacing USRPx

Universal hardware driver (UHD) is meant to be a driver that can interface with any devices (USRP1, USRP2, N210 etc.). And in gnuradio-companion, there is a wrapper called UHD with only a source and a sink. There is an option called "Device Addr" in either UHD block, which I thought it would be the ip address of my USRP2. Then it gave me error of "RuntimeError: ValueError: invalid args string: 192.168.10.2". Going through the c++ code for uhd_usrp_sink couldn't help me understand what args string would be valid, but googling for an image of the UHD USRP sink block (http://old.nabble.com/GNURadio--%3E-UHD-transition-LFRX-(Ubuntu,-Karmic)-td30542095.html) indicates that I should have left the blank empty. And it runs happily after.

How weird.