Laravel default auth module translation - laravel-5

Question

I have generated the default Laravel auth module.
Everywhere in the blades of the module, I see Double Underscore __ function assuming that translation is almost there.
for example
<li>
<a class="nav-link" href="{{ route('login') }}">
{{ __('Login') }}
</a>
</li>
My question: Where is the translation file? Where should I put it, if I create one?
I mean, if I go to the Laravel documentation site there are examples like this
echo __('messages.welcome');
with explanations
For example, let's retrieve the welcome translation string from the resources/lang/messages.php language file:
BUT in my example above there is no file name specified. It is only text:
__('Login')
Question is: What is used for the language file if no file specified? Is there any default? Where does it sit? Where was it set?

Answer 1

All the language translation files in Laravel should be stored in PROJECT_DIRECTORY/resources/lang. When you make an Auth with artisan, it automatically creates it. But if you can't find it, then create manually.
(1)
There's a way to using translation strings as keys by the docs. In this method you can create a JSON file in PROJECT_DIRECTORY/resources/lang with the name of your local, for example for Spanish name it es.json or German de.json, it depends on your local name.
Now create a JSON object and put the translations with the string name you used in your blade:
{
"Login": "Welcome to Login Page!",
"Logout": "You are logged out!",
}
Then use the PHP double underscores method to call your translations in blades:
{{ __('Login') }}
(2)
Create a file named auth.php in PROJECT_DIRECTORY/resources/lang directory. then put a simple php array like this on it:
<?php
return [
/*
Translations go here...
*/
];`
Then add your translate strings to it:
<?php
return [
'Login' => 'Welcome to Login Page!',
'Logout' => 'You are logged out!',
];`
Now in the blade template simply do this:
<li>
<a class="nav-link" href="{{ route('login') }}">
{{ __('auth.Login') }}
</a>
</li>

Answer 2

Laravel Docs
Have an instruction about the json file. Yes it is not php, but json file. Example would be:
resources/lang/es.json
content
{
"I love programming.": "Me encanta programar."
}
Usage
echo __('I love programming.');

Answer 3

It looks like there are no translation file for the default __('Login'), __('Register'), ... provided by laravel.
By default if no translation is found for __('foobar'), laravel just uses the string in the parentheses. So here, assuming there is no translation file, __('Login') is expanded to 'Login'.