code: func getModifiedLabels(a, b map[string]string) sets.String {
  	modified := sets.NewString()
  	for k, v1 := range a {
  		if v2, ok := b[k]; !ok || v1 != v2 {
  			modified.Insert(k)
  		}
  	}
  	for k, v1 := range b {
  		if v2, ok := a[k]; !ok || v1 != v2 {
  			modified.Insert(k)
  		}
  	}
  	return modified
  }
docs: // getModifiedLabels returns the set of label keys that are different between the two maps