function scrollTo(target, callback_before, callback_after) {

            settings.onBeforeMove.call();

            if (typeof callback_before === 'function') {
                callback_before.call();
            }

            $.when($('html,body').animate({
                scrollTop: target
            }, {
                duration: settings.speed
            })).then(function() {
                if (typeof callback_after === 'function') {
                    callback_after.call();
                }
                settings.onAfterMove.call();
            });

        }
a setting to establish the callback after section movement.
             @property onAfterGoSection
             @type Function
             @default Function