irb(main):001:0> class Greeter
irb(main):002:1>   def initialize(name = "World")
irb(main):003:2>     @name = name
irb(main):004:2>   end
irb(main):005:1>   def say_hi
irb(main):006:2>     puts "Hi #{@name}"
irb(main):007:2>   end
irb(main):008:1> end
=> nil
irb(main):009:0> g=Greeter.new("Pat")
=> #<Greeter:0x652be20 @name="Pat">
irb(main):010:0> g.say_hi
Hi Pat
=> nil