def get_stream_url(self, session_id, stream_id=None):
        """ this method returns the url to get streams information """
        url = self.api_url + '/v2/project/' + self.api_key + '/session/' + session_id + '/stream'
        if stream_id:
            url = url + '/' + stream_id
        return url
this method returns the url to get streams information