<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def __set_status(self, value):
        '''
        Sets the deliveries status of this method.
        @param value: str
        '''
        if value not in [DELIVERY_METHOD_STATUS_PENDING,
                         DELIVERY_METHOD_STATUS_SENT,
                         DELIVERY_METHOD_STATUS_CONFIRMED,
                         DELIVERY_METHOD_STATUS_BOUNCED]:
            raise ValueError("Invalid deliveries method status '%s'" % value)

        self.__status = value