code: function wrapElements(els, wrapper) {
    var wrapperEl = document.createElement(wrapper);
  
    // make sure elements are in an array
    if (els instanceof HTMLElement) {
      els = [els];
    } else {
      els = Array.prototype.slice.call(els);
    }
  
    _each(els, function (el) {
      // put it into the wrapper, remove it from its parent
      el.parentNode.removeChild(el);
      wrapperEl.appendChild(el);
    });
  
    // return the wrapped elements
    return wrapperEl;
  }
docs: wrap elements in another element
  @param {NodeList|Element} els
  @param {string} wrapper
  @returns {Element} wrapperEl