public function transform($node)
    {
        if (null === $node) {
            return;
        }

        if (!$node instanceof NodeInterface) {
            throw new UnexpectedTypeException($node, NodeInterface::class);
        }

        return $node->getIdentifier();
    }
public function transform($node)
    {
        if (null === $node) {
            return;
        }

        if (!$node instanceof NodeInterface) {
            throw new UnexpectedTypeException($node, NodeInterface::class);
        }

        return $node->getIdentifier();
    }
public function transform ( $ node ) { if ( null === $ node ) { return ; } if ( ! $ node instanceof NodeInterface ) { throw new UnexpectedTypeException ( $ node , NodeInterface :: class ) ; } return $ node -> getIdentifier ( ) ; }
Transform a node into a uuid.

@param NodeInterface|null $node

@return string|null the uuid to the node or null if $node is null

@throws UnexpectedTypeException if given value is not a NodeInterface
Transform a node into a uuid .