gistfile1.rb

class C
  def initialize(x)
    @x = x
  end

  def each(&block)
    @x.times(&block) 
  end

  include Enumerable
end

# example simplistic implementation for Enumerable
module Enumerable
  def map(&block)
    res = []
    each do |el|
      res << block.call(el)
    end
    res
  end

  def select(&block)
    res = []
    each do |el|
      res << el if block.call(el)
    end
  end

  def group_by(&block)
    res = {}
    each do |el|
      key = block.call(el)
      res[key] ||= []
      res[key] << el
    end
  end

end