package control // Option specifies Server's optional parameter. type Option func(*options) type options struct { allowedKeys [][]byte } func defaultOptions() *options { return new(options) } // WithAllowedKeys returns option to add public keys // to white list of the Control service. func WithAllowedKeys(keys [][]byte) Option { return func(o *options) { o.allowedKeys = append(o.allowedKeys, keys...) } }