Inheritance: extends Illuminate\Database\Eloquent\Model
 public function vote($id)
 {
     $user = Auth::user();
     $entry = ContestEntry::findOrFail($id);
     $contest = Contest::with('entries')->with('entries.contest')->findOrFail($entry->contest_id);
     priv_check('ContestVote', $contest)->ensureCan();
     $contest->vote($user, $entry);
     return $contest->defaultJson($user);
 }