Time.zone = 'London'

def notification_times
  Enumerator.new do |y|
    [1, 2].each do | n|
      y << n.hours.from_now
    end
  end
end

puts notification_times.first # 2020-09-22 15:22:43 +0100
puts notification_times.next # 2020-09-22 14:22:43 UTC