ruby-debug User guide

Hi,
i am using ruby-debug for some time, it's a great tool but i didn't know how much until i bumped this great 30 seconds guide to ruby-debug which is filled with useful information.
a must, for a ruby developer

.not proxy for ruby

a post in Powdered Non Sequitur Man made it possible.
".not" proxy for ruby
so no more

!cond

but,

object.attribute.not.nil?