public new static bool TryCreate(string postalCode, out PostalCode result, out string failureReason)
        {
            var specification = new PostOfficeBoxPostalCodeSpecification();
            if (specification.IsSatisfiedBy(postalCode))
            {
                result = new PostOfficeBoxPostalCode(postalCode);
                failureReason = string.Empty;
                return true;
            }

            result = null;
            failureReason = specification.GetReasonsForDissatisfactionSeparatedWithNewLine();
            return false;
        }
 protected bool Equals(PostalCode other)
 {
     return postalCode.Equals(other.postalCode);
 }