Module 05:
Control, Data Sources, and Formatting

Despite its title, Chapter 5 has little to do with earthquakes, floods, and natural disasters—unless one considers the stock market to be a natural disaster, but then, if that's a disaster, it's a human-made one, right?

The chapter covers a hodge-podge of topics:

• The most important of them have to do with the flow of control in our programs: the concept of indefinite iteration or indefinite looping, the while statement that enables us to use this concept in Python, and list comprehensions, which allow us to create lists by describing their contents rather than prescribing how to build them from data.
• Data sources (files and web pages) are also important.
• Least important, but still useful, is the matter of formatting strings, which enables us to control, for example, the presentation of numbers in computer output (5.7 or 5.70000).