How-to subscribe to addWordToUserDictionary and deleteWordFromUserDictionary action

window.WEBSPELLCHECKER_CONFIG = {
    autoSearch: true,
    ....,
    onLoad: function(instance) {
        instance.subscribe('addWordToUserDictionary', function(data) {
            // Get the added `word` from `data.word` field
        });

        instance.subscribe('deleteWordFromUserDictionary', function(data) {
            // Get the deleted `word` from `data.word` field
        });
    }
};