def GetPublicTimeline(self, since_id=None):
    '''Fetch the sequnce of public twitter.Status message for all users.

    Args:
      since_id:
        Returns only public statuses with an ID greater than (that is,
        more recent than) the specified ID. [Optional]

    Returns:
      An sequence of twitter.Status instances, one for each message
    '''
    parameters = {}
    if since_id:
      parameters['since_id'] = since_id
    url = TWITTER_API_ROOT + 'statuses/public_timeline.json'
    json = self._FetchUrl(url,  parameters=parameters)
    data = simplejson.loads(json)
    self._CheckForTwitterError(data)
    return [Status.NewFromJsonDict(x) for x in data]
Fetch the sequnce of public twitter.Status message for all users.

    Args:
      since_id:
        Returns only public statuses with an ID greater than (that is,
        more recent than) the specified ID. [Optional]

    Returns:
      An sequence of twitter.Status instances, one for each message
    
twitter/twitter.py