Can a nation's entire economy fit on one smartphone app? In China, that day is almost here. More than 700 million Chinese -- more than double the entire U.S. population -- use WeChat. It's an all-purpose super-app that does the job of Facebook, Uber, Paypal, Tinder and many other apps, making it an invaluable tool for the Asian nation's rising middle class. That's helped give WeChat's parent Tencent, a stock-market valuation larger than any other company outside the U.S. -- even bigger than Wal-Mart. But does WeChat actually contribute to China's GDP? Or are there better ways to measure its value? Economist Gan Li, who splits his time between the U.S. and China, and Dune Lawrence, a former Bloomberg correspondent in Beijing, join Kate and Scott to pin down the answers.