Register and append the DOM elements needed and set the event listeners
@param   {HTMLCollection}  containers empty elements to initialize marky marked into
function markymark(container = document.getElementsByTagName('marky-mark')) {
  if (container instanceof HTMLElement) {
    return initializer(container);
  }

  if (!(container instanceof Array) && !(container instanceof HTMLCollection) && !(container instanceof NodeList)) {
    throw new TypeError('argument should be an HTMLElement, Array, HTMLCollection');
  }

  return Array.from(container).map(initializer);
}