old_contents: class BaseCacheModule(object):
      def get(self, key):
          raise NotImplementedError("Subclasses of {} must implement the '{}' method".format(self.__class__.__name__, self.__name__))
  
      def set(self, key, value):
          raise NotImplementedError("Subclasses of {} must implement the '{}' method".format(self.__class__.__name__, self.__name__))
  
      def keys(self):
          raise NotImplementedError("Subclasses of {} must implement the '{}' method".format(self.__class__.__name__, self.__name__))
  
      def contains(self, key):
          raise NotImplementedError("Subclasses of {} must implement the '{}' method".format(self.__class__.__name__, self.__name__))
  
      def delete(self, key):
          raise NotImplementedError("Subclasses of {} must implement the '{}' method".format(self.__class__.__name__, self.__name__))
  
      def flush(self):
          raise NotImplementedError("Subclasses of {} must implement the '{}' method".format(self.__class__.__name__, self.__name__))
  
new_contents: import exceptions
  
  class BaseCacheModule(object):
  
      def get(self, key):
          raise exceptions.NotImplementedError
  
      def set(self, key, value):
          raise exceptions.NotImplementedError
  
      def keys(self):
          raise exceptions.NotImplementedError
  
      def contains(self, key):
          raise exceptions.NotImplementedError
  
      def delete(self, key):
          raise exceptions.NotImplementedError
  
      def flush(self):
          raise exceptions.NotImplementedError
  
subject: Standardize exception handling