Sidebar 1. Instructions for Executing launcher.rb in Unix and Windows
On Unix systems you can set the file as executable and call it directly:

$ chmod u+x launcher.rb
$ ./launcher.rb

Windows users have a leg up here if they used the so-called One-Click Ruby Installer. It takes a few more clicks than one, but in the end it sets up an association for .rb files. So a Windows user should be able to execute the app straight off as follows:

C:\some\dir> launcher.rb

However, Windows users should also know that though they can launch a Ruby file by double clicking on it from the Windows file explorer, the results are fleeting: code will execute in a command shell, which will remain visible only so long as the application is running. For the sake of this demonstration, it's best to run the file from a command shell.