How can I get access to all language keys in Laravel ioC container?

I am using Laravel 5.1. I can't upgrade to Laravel 5.3.

Laravel 5.3 has a function called addLines in the Lang facade the allow me to add Lang keys to the collection in memory.

But Laravel 5.1 and 5.2 do not have such a method. I want to be able to have a method in my code that allows me to do the same thing.

However, I am struggling to find a way to obtain the Lang keys as array where I can add keys to it.

How can I get the actual Lang keys collection so I can add keys to it at run time?

via Chebli Mohamed