How to call libraries in config file

I would just use an English key in the config array, i.e. "profile" and then on the view side of things, call the lang line, e.g.

PHP Code:

foreach($config['menu'] as $key => $value) {
 echo $this->lang->line($key);
} 


Thats a good idea and works for my menu names. but i have another arrays which the first item is like

PHP Code:

$config['country'] = array(
    ''                        =>    'Pick a Country', 


And im using the array like this

PHP Code:

echo form_dropdown(array(
   'name'            =>    'country',
   'placeholder'    =>    $this->lang->line('placeholder_country'),
   ),
   $country,
   set_value('country', $get_user->COUNTRY)
   ); 


How can be translate the 'Pick a Country' ?