Set up on_change events for bokeh server interactions.

def set_server_callback(self, handle):
        """
        Set up on_change events for bokeh server interactions.
        """
        if self.on_events:
            for event in self.on_events:
                handle.on_event(event, self.on_event)
        if self.on_changes:
            for change in self.on_changes:
                if change in ['patching', 'streaming']:
                    # Patch and stream events do not need handling on server
                    continue
                handle.on_change(change, self.on_change)