code: func (h HeartbeatMode) String() string {
  	switch h {
  	case HeartbeatModeNode:
  		return "Node"
  	case HeartbeatModeProxy:
  		return "Proxy"
  	case HeartbeatModeAuth:
  		return "Auth"
  	default:
  		return fmt.Sprintf("<unknown: %v>", int(h))
  	}
  }
docs: // String returns user-friendly representation of the mode