old_contents: #!/usr/bin/python
  #coding:utf8
  
  __author__ = ['markshao']
  
  
  class Machine(object):
      def __init__(self):
          pass
new_contents: #!/usr/bin/python
  #coding:utf8
  
  __author__ = ['markshao']
  
  
  class Machine(object):
      def __init__(self, host, username, password):
          self.host = host
          self.username = username
          self.password = password
  
subject: add some code for machine