singleton class

 def to_singleton(self):
if self.__instance is not None:
 return self.__instance
return super(SingletoCls, self).

class SingletoCls:
  """
  创建单实例类 "SingletoCls"
  """
  __instance = None

  def __new__(cls, *args, **kwargs):
    if cls.__instance:
      return cls.__instance
    else:
      return object.__new__(cls, *args, **kwargs)