code: func nodeConditionsLastObservedAt(nodeConditions []v1.NodeConditionType, lastObservedAt nodeConditionsObservedAt, now time.Time) nodeConditionsObservedAt {
  	results := nodeConditionsObservedAt{}
  	// the input conditions were observed "now"
  	for i := range nodeConditions {
  		results[nodeConditions[i]] = now
  	}
  	// the conditions that were not observed now are merged in with their old time
  	for key, value := range lastObservedAt {
  		_, found := results[key]
  		if !found {
  			results[key] = value
  		}
  	}
  	return results
  }
docs: // nodeConditionsLastObservedAt merges the input with the previous observation to determine when a condition was most recently met.