UML diagram for NodeJS

How would you design code in NodeJS with callbacks in UML?

For example

var module = require('module');

function myfunction(param1, param2, function() {
    module.foo(param1, function(result1) {
        console.log(result1);
        module.bar(param2, function(result2) {
            console.log(result2);
        });
    });
});

I understand the concepts of sequence and activity diagrams, but how would you do a callback like above? The only objects I am using are third party moI am not specificly using objects, almost all of it will be modules.

Thanks