How to use the phylib.io.array._flatten function in phylib

def plot(self, **kwargs):
        """Update the view with the current cluster selection."""
        if not self.cluster_ids:
            return
        bunchs = self.get_clusters_data()
        if not bunchs:
            return

        # All channel ids appearing in all selected clusters.
        channel_ids = sorted(set(_flatten([d.channel_ids for d in bunchs])))
        self.channel_ids = channel_ids
        if bunchs[0].data is not None:
            self.wave_duration = bunchs[0].data.shape[1] / float(self.sample_rate)
        else:  # pragma: no cover
            self.wave_duration = 1.

        # Channel labels.
        channel_labels = {}
        for d in bunchs:
            chl = d.get('channel_labels', ['%d' % ch for ch in d.channel_ids])
            channel_labels.update({
                channel_id: chl[i] for i, channel_id in enumerate(d.channel_ids)})

        # Update the Boxed box positions as a function of the selected channels.
        if channel_ids:
            self.canvas.boxed.update_boxes(_get_box_pos(bunchs, channel_ids))

def _concatenate_parents_attributes(cls, name):
    """Return the concatenation of class attributes of a given name among all parents of a
    class."""
    return _flatten([getattr(_, name, ()) for _ in inspect.getmro(cls)])