Larave 5.2 App\Http\Controllers\Auth\AuthController@register does not exist

im confused, when i php artisan route:list in laravel 5.2 i get a bunch of URLs and methods which are executed by visiting the specific url. for example, when i visit laravel.app/register it shows registration form, i can find the controller but not the function(method) called ShowRegistrationForm. where can i find that ShowRegistrationForm ? i just dont see how it works.

| Domain | Method   | URI                     | Name | Action                                                          | Middleware |
+--------+----------+-------------------------+------+-----------------------------------------------------------------+------------+
|        | GET|HEAD | /                       |      | Closure                                                         |            |
|        | GET|HEAD | articles                |      | App\Http\Controllers\ArticlesController@index                   | web        |
|        | GET|HEAD | articles/create         |      | App\Http\Controllers\ArticlesController@create                  | web        |
|        | POST     | articles/store          |      | App\Http\Controllers\ArticlesController@store                   | web        |
|        | PATCH    | articles/{id}           |      | App\Http\Controllers\ArticlesController@update                  | web        |
|        | GET|HEAD | articles/{id}           |      | App\Http\Controllers\ArticlesController@show                    | web        |
|        | GET|HEAD | articles/{id}/edit      |      | App\Http\Controllers\ArticlesController@edit                    | web        |
|        | GET|HEAD | home                    |      | App\Http\Controllers\HomeController@index                       | web,auth   |
|        | GET|HEAD | login                   |      | App\Http\Controllers\Auth\AuthController@showLoginForm          | web,guest  |
|        | POST     | login                   |      | App\Http\Controllers\Auth\AuthController@login                  | web,guest  |
|        | GET|HEAD | logout                  |      | App\Http\Controllers\Auth\AuthController@logout                 | web        |
|        | POST     | password/email          |      | App\Http\Controllers\Auth\PasswordController@sendResetLinkEmail | web,guest  |
|        | POST     | password/reset          |      | App\Http\Controllers\Auth\PasswordController@reset              | web,guest  |
|        | GET|HEAD | password/reset/{token?} |      | App\Http\Controllers\Auth\PasswordController@showResetForm      | web,guest  |
|        | GET|HEAD | register                |      | App\Http\Controllers\Auth\AuthController@showRegistrationForm   | web,guest  |
|        | POST     | register                |      | App\Http\Controllers\Auth\AuthController@register               | web,guest 

via Chebli Mohamed