old_contents: from letsencrypt.client import logger
  
  
  class Challenge(object):
      def __init__(self, configurator):
          self.config = configurator
      def perform(self, quiet=True):
          logger.error("Error - base class challenge.perform()")
      def generate_response(self):
          logger.error("Error - base class challenge.generate_response()")
      def clean(self):
          logger.error("Error - base class challenge.clean()")
  
new_contents: class Challenge(object):
  
      def __init__(self, configurator):
          self.config = configurator
  
      def perform(self, quiet=True):
          raise NotImplementedError()
  
      def generate_response(self):
          raise NotImplementedError()
  
      def cleanup(self):
          raise NotImplementedError()
  
subject: Clean challenge module.