谁能帮我解释一下

Question

 public IEnumerable<RuleViolation> GetRuleViolations() {            if (String.IsNullOrEmpty(Title))
                yield return new RuleViolation("Title is required", "Title");            if (String.IsNullOrEmpty(Description))
                yield return new RuleViolation("Description is required", "Description");            if (String.IsNullOrEmpty(HostedBy))
                yield return new RuleViolation("HostedBy is required", "HostedBy");            if (String.IsNullOrEmpty(Address))
                yield return new RuleViolation("Address is required", "Address");            if (String.IsNullOrEmpty(Country))
                yield return new RuleViolation("Country is required", "Address");            if (String.IsNullOrEmpty(ContactPhone))
                yield return new RuleViolation("Phone# is required", "ContactPhone");            if (!PhoneValidator.IsValidNumber(ContactPhone, Country))
                yield return new RuleViolation("Phone# does not match country", "ContactPhone");            yield break;
        }这是代码，应该看的明白吧