## Method - [`DefaultIfEmpty<TSource>(IEnumerable<TSource>, TSource)`](https://docs.microsoft.com/en-us/dotnet/api/system.linq.enumerable.defaultifempty?view=netcore-3.1#System_Linq_Enumerable_DefaultIfEmpty__1_System_Collections_Generic_IEnumerable___0____0_) - [`DefaultIfEmpty<TSource>(IEnumerable<TSource>)`](https://docs.microsoft.com/en-us/dotnet/api/system.linq.enumerable.defaultifempty?view=netcore-3.1#System_Linq_Enumerable_DefaultIfEmpty__1_System_Collections_Generic_IEnumerable___0__)
