static void Main(string[] args)
        {
            IEnumerable<string> errors = GetErrors();
            foreach (string error in errors)
            {
                Console.WriteLine(error);
            }
            Console.ReadKey();
        }

        private static IEnumerable<string> GetErrors()
        {
            return GetMoreErrors().Concat(GetOtherErrors())
                                      .Concat(GetValidationErrors())
                                      .Concat(AnyMoreErrors())
                                      .Concat(ICantBelieveHowManyErrorsYouHave());
        }

        private static IEnumerable<string> GetMoreErrors()
        {
            Console.WriteLine("Within GetMoreErrors");
            yield return "GetMoreErrors";
        }

        private static IEnumerable<string> GetOtherErrors()
        {
            Console.WriteLine("Within Method GetOtherErrors");
            yield return "OtherErrors";
        }

        private static IEnumerable<string> GetValidationErrors()
        {
            Console.WriteLine("Within GetValidationErrors");
            yield return "GetValidationErrors";
        }

        private static IEnumerable<string> AnyMoreErrors()
        {
            Console.WriteLine("Within AnyMoreErrors");
            yield return "AnymoreErrors";
        }

        private static IEnumerable<string> ICantBelieveHowManyErrorsYouHave()
        {
            Console.WriteLine("Within ICantBelieveHowManyErrorsYouHave");
            yield return "ICantBelieveHowManyErrorsYouHave";
        }

Output:
Within GetMoreErrors
GetMoreErrors
Within Method GetOtherErrors
OtherErrors
Within GetValidationErrors
GetValidationErrors
Within AnyMoreErrors
AnymoreErrors
Within ICantBelieveHowManyErrorsYouHave
ICantBelieveHowManyErrorsYouHave