public function valid()
    {
        if ($this->items === null) {
            return false;
        }
        $key = key($this->items);
        return ($key !== null && $key !== false);
    }
public function valid()
    {
        if ($this->items === null) {
            return false;
        }
        $key = key($this->items);
        return ($key !== null && $key !== false);
    }
public function valid ( ) { if ( $ this -> items === null ) { return false ; } $ key = key ( $ this -> items ) ; return ( $ key !== null && $ key !== false ) ; }
Checks if current position is valid.

@return boolean
Checks if current position is valid .