Let's recap a bit and plan our next action before diving back into our text editor application.
We know that in order to add syntax highlighting, we will need to change the color of certain words which are considered keywords within the Python programming language. In order to change their colors, we must apply a tag to the range at which they appear within the Text widget.
Tkinter's indexing system is now familiar to us. We know that the general syntax is line number, full stop, and character number, and some special strings also exists which reduce the need to use mathematical calculations upon those numbers. This means we know exactly how to format the ranges to add our tags to.
In order to ...