(04:57 PM) jsharpe@mba:~/ $ irb
ruby-1.9.2-p290 :001 > require 'ipaddr' ; IPAddr.instance_method(:initialize).source_location
 => ["/Users/jsharpe/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/ipaddr.rb", 453]
ruby-1.9.2-p290 :003 > exit
(04:58 PM) jsharpe@mba:~/ $ ruby -e "require 'ipaddr' ; puts IPAddr.instance_method(:initialize).source_location"
/Users/jsharpe/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/ipaddr.rb
453