code: def add_timer(self, name, timer=None):
      if name in self._timers:
          raise ValueError("timer %s already exists" % name)
      timer = timer or Timer()
      self._timers[name] = timer
      return timer
  
imports: import sys
  import time
  import six
label_desc: Use image node_id 3 for calling the TimersMixin obj's underlying member method code with example usage: obj.add_timer(name, timer) and returns: timer