def update(self, kf, detection):
        """Perform Kalman filter measurement update step and update the feature
        cache.
        Parameters
        ----------
        kf : kalman_filter.KalmanFilter
            The Kalman filter.
        detection : Detection
            The associated detection.
        """
        self.mean, self.covariance = kf.update(
            self.mean, self.covariance, detection.to_xyah())
        self.features.append(detection.feature)

        self.hits += 1
        self.time_since_update = 0
        if self.state == TrackState.Tentative and self.hits >= self._n_init:
            self.state = TrackState.Confirmed
Perform Kalman filter measurement update step and update the feature
        cache.
        Parameters
        ----------
        kf : kalman_filter.KalmanFilter
            The Kalman filter.
        detection : Detection
            The associated detection.
        
trackers/deepsort_tracker/track.py