This isn't a book quite like any you've ever owned before, so a brief user manual might be helpful.
Study, practice, then rest. If you're intent on mastering the fundamentals of Python, as opposed to just getting a feel for the language, work with this book and the online exercises in a 15-to-25- minute session, then take a break. Study a chapter for 5 to 10 minutes. Immediately go to the online link given at the end of each chapter and code for 10 to 15 minutes, practicing the lesson until you've coded everything correctly. Then take a walk.
Do the coding exercises on a physical keyboard. A mobile device can be ideal for reading, but it's no way to code. Very, very few Web developers would attempt to do their work on a phone. The same thing goes for learning to code. Theoretically, most of the interactive exercises could be done on a mobile device. But the idea seems so perverse that I've disabled online practice on tablets, readers, and phones.
If you have an authority problem, try to get over it. When you start doing the exercises, you'll find that I can be a pain about insisting that you get every little detail right. For example, if you omit spaces where spaces belong, the program monitoring your work will tell you the code isn't correct, even though it might still run perfectly. Do I insist on having everything just so because I'm a control freak? No, it's because I have to place a limit on harmless maverick behavior in order to automate the exercises. If I were to grant you as much freedom as you might like, creating the algorithms that check your work would be, for me, a project of frightening proportions. Besides, learning to write code with fastidious precision helps you learn to pay close attention to details, a fundamental requirement for coding in any language.
Subscribe, temporarily, to my formatting biases. Current code formatting is like seventeenth-century spelling. Everyone does it his own way. There are no universally accepted standards. But the algorithms that check your work when you do the interactive exercises need standards. They can't grant you the latitude that a human teacher could, because, let's face it, algorithms aren't that bright. So I've had to settle on certain conventions. All of the conventions I teach are embraced by a large segment of the coding community, so you'll be in good company. But that doesn't mean you'll be married to my formatting biases forever. When you start coding projects, you'll soon develop your own opinions or join an organization that has a stylebook. Until then, I'll ask you to make your code look like my code.