def _setData(self, data):
    if (self.data is None):
        self.__data = data
        self.__old_data = (2.0 * data)
    else:
        self.__old_data = self.data
        self.__data = data
def _setData(self, data):
    if (self.data is None):
        self.__data = data
        self.__old_data = (2.0 * data)
    else:
        self.__old_data = self.data
        self.__data = data