lib/comparison/presenter.rb
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
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
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.