old_contents: #!/usr/bin/env python
  #-*- coding:utf-8 -*-
  # Author: Kun Huang <academicgareth@gmail.com>
  
  from nova.virt import driver
  class NovaThousandsDriver(driver.ComputeDriver):
      pass
  
new_contents: #!/usr/bin/env python
  #-*- coding:utf-8 -*-
  # Author: Kun Huang <academicgareth@gmail.com>
  
  from nova.virt import driver
  class NovaThousandsDriver(driver.ComputeDriver):
      '''
      Nova Thousands Compute Driver.
      '''
      def __init__(self, virtapi):
          self.virtapi = virtapi
          self._compute_event_callback = None
  
      def init_host(self, host):
          '''raise error when init failed'''
          return 'Im okay'
  
subject: add init and init_host