Found in /includes/misc-functions.php

This filter is used to output the contexts in the select menu on the plugin’s settings page. It can be used to create custom contexts in conjunction with fsb_context_displayed above.

$contexts is passed as an array with the keys being the context name, and value being the “pretty” translatable context name that users will see in the select menu.

add_filter( 'fsb_contexts', 'my_new_context' ); 
function my_new_context( $contexts ){
     $new_context = array(
         'my-context' => __('My Context', 'fsb')
     $contexts = array_merge( $contexts, $new_context );
     return $contexts;