module Calendar
    class << self
      def today
        Time.now
      end
      
      def yesterday
        Time.now - one_day_in_seconds
      end
      
      def day_string(time)
        time.strftime("%F")
      end
      
      private
      
      def one_day_in_seconds; (60 * 60 * 24); end
    end
  end