IsNotNull(firstName, nameof(firstName)),
=> Fill(firstName, lastName);
result.Add(new DifferenceDetails(firstName, firstItem, secondName, otherItem, refIndex));
mockRepo.Set(r => r.GetPeople()).Returns(new[]{new Person(firstName, lastName), new Person(otherName, lastName));
Console.WriteLine($"The name is {GetFullName(firstName, lastName)}");
set => SetProperty(ref firstName, value, onChanged: Changed, onChanging: Changing, validateValue: Validate);
get => new Person(firstName, lastName, dateOfBirth);