public void Chaining_Dictionary()
{
var dict = new System.Collections.Generic.Dictionary <int, int> {
[1] = 2, [3] = 4
};
var sortedDict = new System.Collections.Generic.SortedDictionary <int, int> {
[1] = 2, [3] = 4
};
Assert.IsTrue(dict.SequenceEqual(dict.DefaultIfEmpty()));
Assert.IsTrue(dict.SequenceEqual(dict.DefaultIfEmpty(dict.First())));
Assert.IsTrue(sortedDict.SequenceEqual(sortedDict.DefaultIfEmpty()));
Assert.IsTrue(sortedDict.SequenceEqual(sortedDict.DefaultIfEmpty(sortedDict.First())));
}