analytics.js
function enqueue(fn) {
  window._vis_opt_queue = window._vis_opt_queue || [];
  window._vis_opt_queue.push(fn);
}
function enqueue(fn) {
  window._vis_opt_queue = window._vis_opt_queue || [];
  window._vis_opt_queue.push(fn);
}
function enqueue ( fn ) { window . _vis_opt_queue = window . _vis_opt_queue || [ ] ; window . _vis_opt_queue . push ( fn ) ; }
Add a `fn` to the VWO queue, creating one if it doesn't exist.

@param {Function} fn
Add a fn to the VWO queue creating one if it doesn t exist .