enum.rb

class Person
  attr_reader :name , :age
  def initialize(name,age)
    @name = name
    @age = age
  end
end

class Group
  include Enumerable
  def initialize
    @persons = []
  end
  def add(person)
    @persons << person
    self
  end
  def each
    @persons.each do |person|
      yield person
    end
  end
end