SelectIfNotNull - Like Select, but returns only those mapped results that aren't null. Equivalent to items.Select().Where(x => x != null)

SelectIfNotNull.cs

public static IEnumerable<U> SelectIfNotNull<T, U>(this IEnumerable<T> source, Func<T, U> mapper)
{
  foreach (var sourceItem in source)
  {
    var resultItem = mapper(sourceItem);
    if (resultItem != null)
    {
      yield return resultItem;
    }
  }
}