System.Linq.Expressions.UnaryExpression.FunctionalOp C# (CSharp) Метод

        private UnaryExpression FunctionalOp(Expression operand)
        {
            ExpressionType functional;
            if (NodeType == ExpressionType.PreIncrementAssign || NodeType == ExpressionType.PostIncrementAssign)
            {
                functional = ExpressionType.Increment;
            }
            else
            {
                Debug.Assert(NodeType == ExpressionType.PreDecrementAssign || NodeType == ExpressionType.PostDecrementAssign);
                functional = ExpressionType.Decrement;
            }
            return new UnaryExpression(functional, operand, operand.Type, Method);
        }