private function getBlankNodeId($id = null)
    {
        if ((null !== $id) && isset($this->blankNodeMap[$id])) {
            return $this->blankNodeMap[$id];
        }

        $bnode = '_:b' . $this->blankNodeCounter++;
        $this->blankNodeMap[$id] = $bnode;

        return $bnode;
    }
private function getBlankNodeId($id = null)
    {
        if ((null !== $id) && isset($this->blankNodeMap[$id])) {
            return $this->blankNodeMap[$id];
        }

        $bnode = '_:b' . $this->blankNodeCounter++;
        $this->blankNodeMap[$id] = $bnode;

        return $bnode;
    }
private function getBlankNodeId ( $ id = null ) { if ( ( null !== $ id ) && isset ( $ this -> blankNodeMap [ $ id ] ) ) { return $ this -> blankNodeMap [ $ id ] ; } $ bnode = '_:b' . $ this -> blankNodeCounter ++ ; $ this -> blankNodeMap [ $ id ] = $ bnode ; return $ bnode ; }
Generate a new blank node identifier

If an identifier is passed, a new blank node identifier is generated
for it and stored for subsequent use. Calling the method with the same
identifier (except null) will thus always return the same blank node
identifier.

@param null|string $id If available, existing blank node identifier.

@return string Returns a blank node identifier.
Generate a new blank node identifier