Some of the programs in this book are a little long. Although it is very helpful to learn Python by typing out the source code for these programs, you may accidentally make typos that cause your programs to crash. It may not be obvious where the typo is.
You can copy and paste the text of your source code to the online diff tool on the book’s website. The diff tool will show any differences between the source code in the book and the source code you’ve typed. This is an easy way of finding any typos in your program.
Copying and pasting text is a very useful computer skill, especially for computer programming. There is a video tutorial on copying and pasting at this book’s website at http://invpy.com/copypaste.
The online diff tool is at this web page: invpy.com/diff/pygame. There is also a video tutorial on how to use this tool on the book’s website.