Singleton Design Pattern in Python

class MySingleton:
   __instance = None
   model = None

   @staticmethod
   def getInstance():
      if MySingleton.__instance == None:
         MySingleton()
      return MySingleton.__instance

   def __init__(self):
      if MySingleton.__instance != None:
         """ Raise exception if init is called more than once. """
         raise Exception("This class is a singleton!")
      else:
         MySingleton.__instance = self

   def getModel(self):
        if self.model is None:
            self.model = self.loadDeepLearningModel('model_ver1')
        return self.model

   def loadDeepLearningModel(self, model):
        """ Load deep learning model and return. """