4th Chapter of Updated Pharo by Example ready for review.

4th Chapter of Updated Pharo by Example ready for review.

https://ci.inria.fr/pharo-contribution/view/Books/job/UpdatedPharoByExample/lastSuccessfulBuild/artifact/book-result/UnderstandingMessage/UnderstandingMessage.pdf 


This one was way simpler than the PharoTour and FirstAplication, so I
imagine that the review will be easier too.

Stef
Not thinking too much, just doing.