old_contents: #!/usr/bin/python
  # -*- coding:utf-8 -*-
  # Powered By KK Studio
  
  from BaseHandler import BaseHandler
  
  # 404 Page
  class Page404Handler(BaseHandler):
      def get(self):
          self.render('page/404.html', title="404")
  
  # 500 Page
  class Page500Handler(BaseHandler):
      def get(self):
          self.render('page/500.html', title="500")
  
  # Blank Page
  class BlankHandler(BaseHandler):
      def get(self):
          self.render('page/blank.html', title="Blank")
new_contents: #!/usr/bin/python
  # -*- coding:utf-8 -*-
  # Powered By KK Studio
  
  from BaseHandler import BaseHandler
  
  # 404 Page
  class Page404Handler(BaseHandler):
      def get(self):
          self.render('page/404.html', title="404")
  
  # 500 Page
  class Page500Handler(BaseHandler):
      def get(self):
          self.render('page/500.html', title="500")
  
  # Error Page
  class PageErrorHandler(BaseHandler):
      def get(self):
          self.render('page/error.html', title="Error")
  
  # Blank Page
  class BlankHandler(BaseHandler):
      def get(self):
          self.render('page/blank.html', title="Blank")
subject: Add Error Page Handler