"Print statements are a valid way to debug code."

In 30+ years of programming, vast majority of bugs I've fixed were diagnosed with a few strategically placed print statements.

"I just print values. When I’m developing a program I do tremendous amount of printing. And by the time I take out, or comment out the prints it really is pretty solid. I rarely have to go back." — Ken Thompson in the book Coders at Work by Peter Seibel