code: def _ray_pretask(self, key, object_refs):
      # Executed at the start of the Ray task.
      start_time = timer()
      return start_time
  
imports: import ray
  import dask.array
  from ray.util.dask import RayDaskCallback, ray_dask_get
  from timeit import default_timer
label_desc: Use image node_id 1 for calling the MyTimerCallback obj's underlying member method code with example usage: obj._ray_pretask(key, object_refs) and returns: start_time