LINQ的Union方法

2個集合合併，有相同的只取中其一個:

source code:

int[] a = { 3, 5, 7 };

            int[] b = { 5, 6, 9 };

            var result = a.Union(b);

            result.ForEach(delegate (int n)
            {
                WriteLiteral(n + "<br>");
            });