"I don't do light-hearted," said Mike Cooley with a rueful sort of chuckle. "I don't feel good about writing a song if I don't have something to say. But you've got to remember, there are still plenty of subjects you can write about without always going into topical things."Cooley is best known as the lead guitarist and one of the main songwriters in the Drive-By Truckers, and he's about to embark on a solo tour through Christmas.