What does this Ruby snippet output?

1class Weight
2  include Comparable
3  def initialize(kg) = @kg = kg
4  def <=>(other) = @kg <=> other.instance_variable_get(:@kg)
5  def to_s = "#{@kg}kg"
6end
7w = [Weight.new(10), Weight.new(5), Weight.new(8)]
8puts w.sort.map(&:to_s).inspect
9puts w.min.to_s