code: def arrow
        if positive?
          t 'comparison.arrows.positive_html', default: ARROWS[:up]
        elsif negative?
          t 'comparison.arrows.negative_html', default: ARROWS[:down]
        else
          t 'comparison.arrows.nochange_html', default: ARROWS[:none]
        end
      end
docs: Returns the I18n translation for `comparison.icons`. (See also #icon.)
  
   This method is intended to display a graphical representation of the
   comparison. Typically this would be an arrow pointing up or down.
  
   The default implementation is as follows:
  
       en:
         comparison:
           arrows:
             positive_html: '&uarr;'
             negative_html: '&darr;'
             nochange_html: ''
  
   For example, to generate up and down arrows using Glyphicons included
   with Bootstrap, you could add the following translations to your
   application:
  
   #arrows and its sister method #icon perform roughly identical tasks with
   roughly identical intentions. The difference between the two methods is
   in the context in which they are intended to be used.
  
   #arrows is meant to be used from view contexts with limited functionality
   such as an HTML email. As such, the translations you specify should be
   simple enough, like HTML character entities, to work within said view
   context.
  
   #icons is meant to be used from full-featured view contexts. As such,
   #icons is the one to use to generate HTML tags.