tweak suggested practical order

advanced_topics/README.md

@@ -6,12 +6,13 @@ particular feature of the Python Programming language. They are intended for
 people who are familiar with the basics of Python, and want to learn about
 some of the more advanced features of the language.
 
-Practicals on the following topics are available:
+Practicals on the following topics are available. They can be viewed in any
+order, but we recommend going through them in this order:
 
 * Function inputs and outputs
 * Modules and packages
+* Testing
 * Object-oriented programming
 * Operator overloading
-* Decorators
 * Context managers
-* Testing
+* Decorators