/**
  * Find a model by its primary key.
  *
  * @param  mixed  $id
  * @param  array  $columns
  * @return \Illuminate\Support\Collection|static
  */
 public function find($id)
 {
     $model = Vocabulary::find($id);
     if ($model) {
         return $model;
     }
     throw new ResourceNotFoundException('Vocabulary was not found.');
 }