[jQuery] How to add method to plugin, so it's possible to call it from callbacks?

[jQuery] How to add method to plugin, so it's possible to call it from callbacks?


Hi,
I'm using MultiFile plugin and it allows you to specify callback
functions for events like i.e. afterFileAppend:
$(document).ready(function() {
var addDescription = function(fileInput, descriptionId) {do
something};
$('.multi_image').MultiFile({
afterFileAppend: function(fileInput) {
addDescription(fileInput, 'image_description');
}
});
});
How can I add addDescription method to MultiFile plugin, so I can use
it in all places where I use this plugin?