/**
  * Updates an entity with key $key with
  * the provided data
  *
  * @param $key
  * @param array $data
  * @return mixed
  */
 public function update($key, array $data)
 {
     $user = User::find($key);
     if ($user != null) {
         return $user->update($data);
     }
     return null;
 }