A country hit made by artificial intelligence has climbed to the top of a Billboard chart - a first for the genre. The song, "Walk My Walk," by an artist known as Breaking Rust, is now No. 1 on Billboard's Country Digital Song Sales chart. But the brooding, gravel-voiced cowboy behind the hit doesn't exist. At least, not in the traditional sense. He's an AI creation with millions of streams, tens of thousands of followers and no verifiable human footprint.