    # File lib/active_merchant/billing/integrations/paypal.rb, line 18
            def self.service_url
              mode = ActiveMerchant::Billing::Base.integration_mode
              case mode
              when :production
                self.production_url
              when :test
                self.test_url
              else
                raise StandardError, "Integration mode set to an invalid value: #{mode}"
              end
            end