xNode/Example/Nodes/DisplayValue.cs

using XNode;

namespace BasicNodes {
    public class DisplayValue : XNode.Node {
        protected override void Init() {
            base.Init();
            if (!HasPort("input")) AddInstanceInput(typeof(object), "input");
        }

        public override object GetValue(XNode.NodePort port) {
            return GetInputValue<object>("input");
        }
    }
}