code: public Observable<VerifyResult> verifyFaceToFaceAsync(UUID faceId1, UUID faceId2) {
          return verifyFaceToFaceWithServiceResponseAsync(faceId1, faceId2).map(new Func1<ServiceResponse<VerifyResult>, VerifyResult>() {
              @Override
              public VerifyResult call(ServiceResponse<VerifyResult> response) {
                  return response.body();
              }
          });
      }
docs: Verify whether two faces belong to a same person or whether one face belongs to a person.
  
  @param faceId1 FaceId of the first face, comes from Face - Detect
  @param faceId2 FaceId of the second face, comes from Face - Detect
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the VerifyResult object