ruby 2.0 keyword arguments

kw_args.rb

2.0.0-p451 :016 >   def omg(foo: 42, bar: "hello world!")
2.0.0-p451 :017?>     puts [foo, bar].inspect
2.0.0-p451 :018?>   end
 => nil 
 
2.0.0-p451 :019 > omg
[42, "hello world!"]
 => nil 
 
2.0.0-p451 :020 > omg(1, "one")
ArgumentError: wrong number of arguments (2 for 0)
	from (irb):16:in `omg'
	from (irb):20
	from /Users/francis/.rvm/rubies/ruby-2.0.0-p451/bin/irb:12:in `<main>'
	
2.0.0-p451 :021 > omg(foo: 1, bar: "one")
[1, "one"]
 => nil
 
2.0.0-p451 :022 > omg(zzz: "error!")
ArgumentError: unknown keyword: zzz
	from (irb):22
	from /Users/francis/.rvm/rubies/ruby-2.0.0-p451/bin/irb:12:in `<main>'