code: func validateClusterIPFlags(options *ServerRunOptions) []error {
  	var errs []error
  
  	if options.ServiceClusterIPRange.IP == nil {
  		errs = append(errs, errors.New("no --service-cluster-ip-range specified"))
  	}
  	var ones, bits = options.ServiceClusterIPRange.Mask.Size()
  	if bits-ones > 20 {
  		errs = append(errs, errors.New("specified --service-cluster-ip-range is too large"))
  	}
  
  	return errs
  }
docs: // TODO: Longer term we should read this from some config store, rather than a flag.