Python, for all its power and popularity, has long lacked a form of flow control found in other languages—a way to take a value and match it elegantly against one of a number of possible conditions.

The fastest way to improve at Python is through consistent, hands-on coding. With hundreds of exercises available online, you can progress from basic print statements to advanced data analysis.

But in many cases, it doesn’t have to be an either/or proposition. Properly optimized, Python applications can run with surprising speed—perhaps not as fast as Java or C, but fast enough for web ...