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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def stream(self, callback=None):
 """ Runtime copy of job messages. This required the 'stream` flag to be set to True otherwise it will not be able to copy any output, while it will block until the process exits. :note: This function will block until it reaches end of stream or the process is no longer running. :param callback: callback method that will get called for each received message callback accepts 3 arguments - level int: the log message levels, refer to the docs for available levels and their meanings - message str: the actual output message - flags int: flags associated with this message - 0x2 means EOF with success exit status - 0x4 means EOF with error for example (eof = flag & 0x6) eof will be true for last message u will ever receive on this callback. Note: if callback is none, a default callback will be used that prints output on stdout/stderr based on level. :return: None """

        if callback is None:
            callback = Response.__default

        if not callable(callback):
            raise Exception('callback must be callable')

        queue = 'stream:%s' % self.id
        r = self._client._redis

        # we can terminate quickly by checking if the process is not running and it has no queued output.
        # if not self.running and r.llen(queue) == 0:
        #     return

        while True:
            data = r.blpop(queue, 10)
            if data is None:
                if not self.running:
                    break
                continue
            _, body = data
            payload = json.loads(body.decode())
            message = payload['message']
            line = message['message']
            meta = message['meta']
            callback(meta >> 16, line, meta & 0xff)

            if meta & 0x6 != 0:
                break