public function getIdentifier()
    {
        $identifier = $this->getFromNode()->getIdentifier() 
                    . '-'
                    . $this->getType()
                    . '-'
                    . $this->getToNode()->getIdentifier();
        
        return $identifier;
    }
public function getIdentifier()
    {
        $identifier = $this->getFromNode()->getIdentifier() 
                    . '-'
                    . $this->getType()
                    . '-'
                    . $this->getToNode()->getIdentifier();
        
        return $identifier;
    }
public function getIdentifier ( ) { $ identifier = $ this -> getFromNode ( ) -> getIdentifier ( ) . '-' . $ this -> getType ( ) . '-' . $ this -> getToNode ( ) -> getIdentifier ( ) ; return $ identifier ; }
Returns the unique identifier of this node

@return string
Returns the unique identifier of this node