public function getIterator()
    {
        if (is_null($this->_iterator)) {
            $this->_iterator = new Iterator($this->_items);
        }
        return $this->_iterator;
    }
public function getIterator()
    {
        if (is_null($this->_iterator)) {
            $this->_iterator = new Iterator($this->_items);
        }
        return $this->_iterator;
    }
public function getIterator ( ) { if ( is_null ( $ this -> _iterator ) ) { $ this -> _iterator = new Iterator ( $ this -> _items ) ; } return $ this -> _iterator ; }
return a iterator

@return    IteratorInterface
return a iterator