There's more...

Many of the recipes in the book will introduce the different parts of a script using the REPL. This will give you a chance to get immediate feedback as you run each snippet of code. Once you've entered the different snippets in the REPL you can also use REPL features to assist in your experimentation with the code. You can use the up and down arrow keys to move through the history of commands that have been entered in the REPL. For example, if you had just executed a line of code in the REPL that turned on a specific pixel on the board, you could press the up key and change which pixel is lit up by editing the line and pressing Enter again.