Process change events adding timeout to process multiple concerted
        value change at once rather than firing off multiple plot updates.

def on_change(self, attr, old, new):
        """
        Process change events adding timeout to process multiple concerted
        value change at once rather than firing off multiple plot updates.
        """
        self._queue.append((attr, old, new))
        if not self._active and self.plot.document:
            self.plot.document.add_timeout_callback(self.process_on_change, 50)
            self._active = True