code: func ZonesFromAllowedTopologies(allowedTopologies []v1.TopologySelectorTerm) (sets.String, error) {
  	zones := make(sets.String)
  	for _, term := range allowedTopologies {
  		for _, exp := range term.MatchLabelExpressions {
  			if exp.Key == v1.LabelZoneFailureDomain {
  				for _, value := range exp.Values {
  					zones.Insert(value)
  				}
  			} else {
  				return nil, fmt.Errorf("unsupported key found in matchLabelExpressions: %s", exp.Key)
  			}
  		}
  	}
  	return zones, nil
  }
docs: // ZonesFromAllowedTopologies returns a list of zones specified in allowedTopologies