public abstract class DayInfo
    {
        protected void GetInfoCore()
        {
            throw new System.NotImplementedException();
        }

        //Changed return type to "object" instead of "void"
        public object GetInfo()
        {
            GetInfoCore();
            return null;
        }
    }

    public class DayInfo<T> : DayInfo
    {
        private T info;

        public DayInfo(T data)
        {
            info = data;
        }

        //If this is removed it will default back to the original function from the base class and throw an exception
        public new T GetInfo()
        {
            return info;
        }
    }