Answered simple Js question

$(document).ready(function() {
    $.fn.slideFadeToggle = function(speed, easing, callback) {

        return this.animate({opacity: 'toggle', height: 'toggle'}, speed, easing, callback);
    };
    $('.accordion').accordion({
        //defaultOpen: 'open',
        speed: 'fast',
        animateOpen: function (elem, opts) { 
            elem.children(":first").removeClass('fa fa-angle-down');
            elem.children(":first").toggleClass('fa fa-angle-up');
            elem.next().stop(true, true).slideFadeToggle(opts.speed);
           
        },
        animateClose: function (elem, opts) { 
            elem.children(":first").removeClass('fa fa-angle-up');
            elem.children(":first").toggleClass('fa fa-angle-down');
            elem.next().stop(true, true).slideFadeToggle(opts.speed);
        }
    });
});