/**
* Find a discussion by ID, optionally making sure it is visible to a
* certain user, or throw an exception.
*
* @param integer $id
* @param User $user
* @return \Flarum\Core\Discussions\Discussion
*/
public function findOrFail($id, User $user = null)
{
$query = Discussion::where('id', $id);
return $this->scopeVisibleTo($query, $user)->firstOrFail();
}
