code: func NewWithoutDefaults(ctx context.Context, opts ...Option) (host.Host, error) {
  	var cfg Config
  	if err := cfg.Apply(opts...); err != nil {
  		return nil, err
  	}
  	return cfg.NewNode(ctx)
  }
docs: // NewWithoutDefaults constructs a new libp2p node with the given options but
  // *without* falling back on reasonable defaults.
  //
  // Warning: This function should not be considered a stable interface. We may
  // choose to add required services at any time and, by using this function, you
  // opt-out of any defaults we may provide.