/**
  * Get string representation of the object
  *
  * @return string
  */
 public function getObjectDump()
 {
     if ($this->_dump === null) {
         return '';
     }
     if (is_string($this->_dump)) {
         return $this->_dump;
     }
     return $this->_dump->getRef();
 }

 /**
  * Return object as string
  *
  * @param Zend_Pdf_Factory $factory
  * @return string
  */
 public function toString($factory = null)
 {
     return "stream\n" . $this->value->getRef() . "\nendstream";
 }

 /**
  * Return true if object is locked
  *
  * @return boolean
  */
 public function isLocked()
 {
     return $this->_memContainer->isLocked();
 }