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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 get_timeline(self, auth_secret, max_cnt_tweets):
 """Get the general or user timeline. If an empty authentication secret is given, this method returns the general timeline. If an authentication secret is given and it is valid, this method returns the user timeline. If an authentication secret is given but it is invalid, this method returns an error. Parameters auth_secret: str Either the authentication secret of the logged-in user or an empty string. max_cnt_tweets: int The maximum number of tweets included in the timeline. If it is set to -1, then all the available tweets will be included. Returns ------- bool True if the timeline is successfully retrieved, False otherwise. result A dict containing a list of tweets with the key TWEETS_KEY if the timeline is successfully retrieved, a dict containing the error string with the key ERROR_KEY otherwise. Note ---- Possible error strings are listed as below: - ERROR_NOT_LOGGED_IN """

        result = {pytwis_constants.ERROR_KEY: None}

        if auth_secret == '':
            # An empty authentication secret implies getting the general timeline.
            timeline_key = pytwis_constants.GENERAL_TIMELINE_KEY
        else:
            # Check if the user is logged in.
            loggedin, userid = self._is_loggedin(auth_secret)
            if not loggedin:
                result[pytwis_constants.ERROR_KEY] = pytwis_constants.ERROR_NOT_LOGGED_IN
                return (False, result)

            # Get the user timeline.
            timeline_key = pytwis_constants.USER_TIMELINE_KEY_FORMAT.format(userid)

        result[pytwis_constants.TWEETS_KEY] = self._get_tweets(timeline_key, max_cnt_tweets)
        return (True, result)