public function getContentStream($streamId = null, $offset = null, $length = null)
    {
        return $this->getSession()->getContentStream($this, $streamId, $offset, $length);
    }
public function getContentStream($streamId = null, $offset = null, $length = null)
    {
        return $this->getSession()->getContentStream($this, $streamId, $offset, $length);
    }
public function getContentStream ( $ streamId = null , $ offset = null , $ length = null ) { return $ this -> getSession ( ) -> getContentStream ( $ this , $ streamId , $ offset , $ length ) ; }
Retrieves the content stream that is associated with the given stream ID.
This is usually a rendition of the document.

@param string|null $streamId the stream ID
@param integer|null $offset the offset of the stream or <code>null</code> to read the stream from the beginning
@param integer|null $length the maximum length of the stream or <code>null</code> to read to the end of the
stream
@return StreamInterface|null the content stream, or <code>null</code> if no content is associated with this
stream ID
Retrieves the content stream that is associated with the given stream ID . This is usually a rendition of the document .