public function valid()
    {
        $keys = array_keys($this->tags);
        return isset($keys[$this->position]) && isset($this->tags[$keys[$this->position]]);
    }
public function valid()
    {
        $keys = array_keys($this->tags);
        return isset($keys[$this->position]) && isset($this->tags[$keys[$this->position]]);
    }
public function valid ( ) { $ keys = array_keys ( $ this -> tags ) ; return isset ( $ keys [ $ this -> position ] ) && isset ( $ this -> tags [ $ keys [ $ this -> position ] ] ) ; }
Iterator item exists

@return boolean
Iterator item exists