new_contents: # coding: utf-8
  
  from datetime import datetime
  
  
  class Subject(object):
  
      def __init__(self, id, text, create_time=None, update_time=None):
          self.subject_id = str(id)
          self.subject_text = text
          self.create_time = create_time
          self.update_time = update_time
  
      @classmethod
      def new(cls, text):
          create_time = datetime.now()
          default = {}
          default.update(subject_id='2', subject_text=text,
                  create_time=create_time,
                  update_time=create_time)
          print default
          # TODO:存取条目
  
      @classmethod
      def get_by_id(cls, id):
          # TODO:查询存储系统，然后返回
          pass
  
      @classmethod
      def get_all_subject(cls):
          #TODO:全部返回
          pass
  
      def update(self, text=''):
          update = {}
          if text:
              update.update(text=text)
          if update:
              update.update(update_time=datetime.now())
          #TODO:更新存储系统里面相应条目
  
  
subject: add model of a subject