When I run IRB at a command prompt, I get the message:
“DL is deprecated. Please use Fiddle”
What is Fiddle (a gem?) and how do I use it? Do I need a bow and music
lessons? 
Mine’s in C:\Ruby200\lib\ruby\2.0.0\dl.rb
Comment out the “warn” line in the equivalent file in your installation
and you won’t get that message anymore.
The people who make the (awesome) Ruby Installer for Windows just
haven’t migrated to Fiddle yet. They’ll get around to it.
You’d use it when you make most windows API calls.
Thanks.