Triggers before deleted/unliked.
~~~
<?php
function my_component_init(){
ossn_register_callback('like', 'before:deleted', 'my_component_cb');
}
function my_component_cb($callback, $type, array $params){
//$params[subject_id, type, guid]
}
ossn_register_callback('ossn', 'init', 'my_component_init');
~~~