def imply_dates
      return unless !@properties['end'].nil? && !@properties['start'].nil?

      start_date = nil

      @properties['start'].each do |start_val|
        if start_val =~ /^(\d{4}-[01]\d-[0-3]\d)/
          start_date = Regexp.last_match(1) if start_date.nil?
        elsif start_val =~ /^(\d{4}-[0-3]\d\d)/
          start_date = Regexp.last_match(1) if start_date.nil?
        end
      end

      unless start_date.nil?
        @properties['end'].map! do |end_val|
          if end_val.match?(/^\d{4}-[01]\d-[0-3]\d/)
            end_val
          elsif end_val.match?(/^\d{4}-[0-3]\d\d/)
            end_val
          else
            start_date + ' ' + end_val
          end
        end
      end
    end
def imply_dates
      return unless !@properties['end'].nil? && !@properties['start'].nil?

      start_date = nil

      @properties['start'].each do |start_val|
        if start_val =~ /^(\d{4}-[01]\d-[0-3]\d)/
          start_date = Regexp.last_match(1) if start_date.nil?
        elsif start_val =~ /^(\d{4}-[0-3]\d\d)/
          start_date = Regexp.last_match(1) if start_date.nil?
        end
      end

      unless start_date.nil?
        @properties['end'].map! do |end_val|
          if end_val.match?(/^\d{4}-[01]\d-[0-3]\d/)
            end_val
          elsif end_val.match?(/^\d{4}-[0-3]\d\d/)
            end_val
          else
            start_date + ' ' + end_val
          end
        end
      end
    end
imply date for dt-end if dt-start is defined with a date