fizzbuzz = Enumerator.new { |yielder|
  1.upto(Float::INFINITY) do |n|
    case
      when n % 15 == 0 then yielder << "FizzBuzz"
      when n %  5 == 0 then yielder << "Buzz"
      when n %  3 == 0 then yielder << "Fizz"
      else yielder << n.to_s
    end
  end
}

fizzbuzz.first(30).each do |str|
  puts str
end