docstr: Start the timer.
  Use Tk.after to schedule timer events.
code: def _vispy_start(self, interval):
      """Start the timer.
      Use Tk.after to schedule timer events.
      """
      self._vispy_stop()
      self.last_interval = max(0, int(round(interval * 1000)))
      self._id = self._tk.after(self.last_interval, self._vispy_timeout)
  
imports: from __future__ import division
  from time import sleep
  import warnings
  from ..base import BaseApplicationBackend, BaseCanvasBackend, BaseTimerBackend
  from ...util import keys
  from ...util.ptime import time
  from ...gloo import gl
label_desc: Use image node_id 2 for calling the TimerBackend obj's underlying member method code with example usage: obj._vispy_start(interval) without return types