code: def _time_metrics(self):
      now = datetime.now()
      if self._start_time is None:
          self._start_time = now
      if self._previous_time is None:
          self._previous_time = now
  
      time_elapsed = now - self._start_time
      time_delta = now - self._previous_time
  
      self._previous_time = now
      return (
          now.strftime("%Y-%m-%d %H:%M:%S"),
          time_elapsed.total_seconds(),
          time_delta.total_seconds(),
      )
  
file_path: BayesianOptimization/bayes_opt/observer.py
imports: from datetime import datetime
  from .event import Events
label_desc: Use image node_id 3 for calling the _Tracker obj's underlying member method code with example usage: obj._time_metrics() and returns: now,  time_elapsed,  time_delta