working

    def set_back_url
      return if request.referer.blank?

      if referer_path.include?(city_establishments_path) 
        session['gcd_back_url'] = referer_path
        return
      end
      
      if referer_path.eql?(city_grease_traps_path)
        session['gcd_back_url'] = city_grease_traps_path
        return
      end

      session['gcd_back_url'] ||= city_grease_traps_path
    end