public async Task<Person> UpdateAsync(Person person)
 {
     var localPerson = await FindAsync(person.Id);
     localPerson.First = person.First;
     localPerson.Last = person.Last;
     return localPerson;
 }
 public async Task<Person> CreateAsync(Person person)
 {
     if (await FindAsync(person.Id) != null) throw new Exception("Person already exists");
     var localPerson = new Person
     {
         First = person.First,
         Last = person.Last,
         Id = _people.Count() + 1
     };
     _people.Add(localPerson);
     return localPerson;
 }