public function users_post()
{
// $this->some_model->update_user( ... );
$message = ['id' => 100, 'name' => $this->post('name'), 'email' => $this->post('email'), 'message' => 'Added a resource'];
$this->set_response($message, REST_Controller::HTTP_CREATED);
// CREATED (201) being the HTTP response code
}