code: def update_trial_stats(self, trial, result):
          
  
          assert trial in self._live_trials
          assert self._get_result_time(result) >= 0
  
          delta = self._get_result_time(result) - \
              self._get_result_time(self._live_trials[trial])
          assert delta >= 0
          self._completed_progress += delta
          self._live_trials[trial] = result
docs: Update result for trial. Called after trial has finished
          an iteration - will decrement iteration count.
  
          TODO(rliaw): The other alternative is to keep the trials
          in and make sure they're not set as pending later.