# File lib/whenever/cron.rb, line 60
      def parse_symbol
        shortcut = case @time
          when *KEYWORDS then "@#{@time}" # :reboot => '@reboot'
          when :year     then Whenever.seconds(12, :months)
          when :day      then Whenever.seconds(1, :day)
          when :month    then Whenever.seconds(1, :month)
          when :week     then Whenever.seconds(1, :week)
          when :hour     then Whenever.seconds(1, :hour)
        end

        if shortcut.is_a?(Numeric)
          @time = shortcut
          parse_time
        elsif shortcut
          if @at.is_a?(Time) || (@at.is_a?(Numeric) && @at > 0)
            raise ArgumentError, "You cannot specify an ':at' when using the shortcuts for times."
          else
            return shortcut
          end
        else
          parse_as_string
        end
      end