code: def __init__(self, name, env=None):
      super(Timer, self).__init__(TIMER_TYPE, name, env)
      self._start = 0
      self._end = 0
  
imports: import time
  from contextlib import contextmanager
  from metaflow.sidecar import Message, MessageTypes, Sidecar
label_desc: Use image node_id 1 to create a new Timer object from inherited base classes: Metric with example: obj = Timer(name, env)