code: def on_timer(self, event):
      self.clock += 0.001 * 1000.0 / 60.0
      self.program["theta"] = self.clock
      self.update()
  
file_path: vispy/examples/gloo/rotating_quad.py
imports: from vispy import gloo, app
  from vispy.gloo import Program
label_desc: Use image node_id 4 for calling the Canvas obj's underlying member method code with example usage: obj.on_timer(event) without return types