code: func thresholdsFirstObservedAt(thresholds []evictionapi.Threshold, lastObservedAt thresholdsObservedAt, now time.Time) thresholdsObservedAt {
  	results := thresholdsObservedAt{}
  	for i := range thresholds {
  		observedAt, found := lastObservedAt[thresholds[i]]
  		if !found {
  			observedAt = now
  		}
  		results[thresholds[i]] = observedAt
  	}
  	return results
  }
docs: // thresholdsFirstObservedAt merges the input set of thresholds with the previous observation to determine when active set of thresholds were initially met.