Use tuples to sort Comparable objects based on multiple properties. Example: sorting contacts by surname; then by name, to see all names from the same family in a row.
Use Swift's property observers to observe and respond to changes in a property’s value. Both `willSet` and `didSet` takes a default parameter to get new and old values
Use a generic type in type aliases to increase code reusability. Notice how the same type alias is used for all Post, [Post], and [Book] 😎
Use the ~= operator in Swift to check for patterns. Say you have an array and you want to get an object at index in a safe way
Respond to appearance changes in system preference live in the browser in macOS 10.14+ and iOS 13+. Hint: try toggling dark mode on and off and observe this website 😉
Make trailing space optional in Django by overriding `SimpleRouter` in your `urls.py`