laravel 5.4 common arrays, constants, common functions?

laravel 5.4, where to put common arrays, constants, common functions, so that it is accessible every where eg. in controller, model, mailables, etc. eg. $common_array = array("1" => "a", "2" => "b");

where to put above array, so that, it can be accessible everywhere just like configuration.

via Chebli Mohamed