public void Trim()
        {
            var ld = new RecentDictionary <string, int>();

            for (int i = 0; i < 1234; i++)
            {
                ld[i.ToString()] = i;
            }

            int initialCap = ld.Capacity;

            Assert.True(initialCap > 1234);

            ld.Trim();
            Assert.Equal(500, ld["500"]);


            ld.Clear();
            ld.Trim();
            Assert.Equal(8, ld.Capacity);
        }