gistfile1.rb

class ItemWithQuantity
  include Enumerable # 1.この組み込みライブラリをinclude

  attr_reader :item, :quantity

  def initialize(item, quantity)
    @item = item
    @quantity = quantity
  end 

  def each            # 2.eachを定義
    quantity.times { yield item }
    self
  end 
end