code: function tag(node, tagName){
      var element = get(node) || document;
  
      if (tagName == '*' && element.all)
        return arrayFrom(element.all);
      else
        return arrayFrom(element.getElementsByTagName(tagName || '*'));
    }
docs: Returns all descendant elements tagName name for node.
  @param {string|Node} node Context element.
  @param {string} tagName Tag name.
  @return {Array.<Element>}