old_contents: 
  class IO:
  
  
      def __init__(self):
          self.__self = self
      #一个单件模式,确保全局只有一个IO对象
      def getIO(self):
         if (self.__self == None) :
             self.__init__()
         else:
             return self.__self
  
      def saveDomain(self,domain):
          pass
      def saveData(self,data):
          pass
      def getData(self):
          pass
      def getDomainWithNumber(self,number):
          pass
  
  
  
  
new_contents: 
  class IO:
  
  
      def __init__(self):
          self.__self = self
      #一个单件模式,确保全局只有一个IO对象
      #有错误，得改改。
      def getIO(self):
         if (self.__self == None) :
             self.__init__()
         else:
             return self.__self
  
      def saveDomain(self,domain):
          pass
      def saveData(self,data):
          pass
      def getData(self):
          pass
      def getDomainWithNumber(self,number):
          pass
  
  
  
  
subject: fix some problems =.= 随便改了几行代码。。。