code: public Observable<Person> getAsync(String personGroupId, UUID personId) {
          return getWithServiceResponseAsync(personGroupId, personId).map(new Func1<ServiceResponse<Person>, Person>() {
              @Override
              public Person call(ServiceResponse<Person> response) {
                  return response.body();
              }
          });
      }
docs: Retrieve a person's information, including registered persisted faces, name and userData.
  
  @param personGroupId Id referencing a particular person group.
  @param personId Id referencing a particular person.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the Person object