public void Test()
        {
            var displayClass = new DisplayClass();
            displayClass.numberToBeAdded = 4;
            var listToProcess = new List<int>();
            ProcessList(listToProcess, displayClass.Test_b__0);
        }

        private sealed class DisplayClass
        {
            public int numberToBeAdded;

            public int Test_b__0(int x)
            {
                return x + numberToBeAdded;
            }
        }