This is a simple example, but usually you have command line arguments, the output can be large, and you might have input to process. As soon as you have that, y

This is a simple example, but usually you have command line arguments, the output can be large, and you might have input to process. As soon as you have that, you arrive at a more complex API, but one where you don't shoot yourself in the foot so easily (e.g. with special characters in file names and friends).