_hideElement(element: HTMLElement) {
    if (this.options.class.visible) {
      element.classList.remove(this.options.class.visible);
    }
    if (!element.classList.contains(this.options.class.hidden)) {
      element.classList.add(this.options.class.hidden);
      this.hidden++;

      if (typeof this.options.onHidden === 'function') {
        this.options.onHidden(element);
      }
    }
    if (this.options.hiddenAttr) {
      element.setAttribute('hidden', 'true');
    }
    if (this.options.mark) {
      element.innerHTML = element.innerHTML.replace(/<\/?mark>/g, '');
    }
  }
Hide an element
@function _hideElement
@param  {HTMLElement} element the element to hide
@memberOf holmes
@private