string $token:
Profile[] An array of Profile instances
protected function readChildren($token) {
  $profiles = array();
  $cursor = $this
    ->getMongo()
    ->find(array(
    'parent' => $token,
    'data' => array(
      '$exists' => true,
    ),
  ));
  foreach ($cursor as $d) {
    $profiles[] = $this
      ->getProfile($this
      ->getData($d));
  }
  return $profiles;
}