old_contents: class SNMPCommand(object):
  
      def __init__(self):
          pass
  
      def get(self):
          pass
  
      def set(self):
          pass
  
      def walk(self):
          pass
  
      def bulkget(self):
          pass
  
      def bulkwalk(self):
          pass
  
new_contents: import abc
  
  class SNMPCommand(object, metaclass=abc.ABCMeta):
  
      def __init__(self):
          pass
  
      def get(self):
          pass
  
      def set(self):
          pass
  
      def walk(self):
          pass
  
  
  class SNMPCommandV1(SNMPCommand):
  
      def __init__(self):
          pass
  
      def get(self):
          pass
  
      def set(self):
          pass
  
      def walk(self):
          pass
  
  
  class SNMPCommandV2(SNMPCommandV1):
  
      def __init__(self):
          pass
  
      def get(self):
          pass
  
      def set(self):
          pass
  
      def walk(self):
          pass
  
      def bulkget(self):
          pass
  
      def bulkwalk(self):
          pass
  
subject: add toami/request.py