How can I use irb the Ruby interpreter to test/debug my `.rb` files? I want to load an `.rb` file, let it run, and after it ends, get back to the irb prompt so I would be able to manipulate the variables which my script has built.

I tried `load`, `require`, and `irb -r`, but none of them worked as I would like. After the execution, when the program terminates, I get an irb prompt, but all of the variables are inaccessible. What can I do?