YUI3 calling a function

Question

top.on('click', function(){
    anim.run();
});

I have an anim function, and was wondering why I can't call it like this

top.on('click', anim.run);

Answer 1

top.on('click', function () { anim.run(); });

or

top.on('click', Y.bind(anim.run, anim));