gan_node_html.php
function getSibling($offset = 1) {
		$index = $this->index() + $offset;
		if (($index >= 0) && ($index < $this->parent->childCount())) {
			return $this->parent->getChild($index);
		} else {
			return null;
		}
	}
function getSibling($offset = 1) {
		$index = $this->index() + $offset;
		if (($index >= 0) && ($index < $this->parent->childCount())) {
			return $this->parent->getChild($index);
		} else {
			return null;
		}
	}
Get sibling node
@param int $offset Offset from current node
@return DomNode Null if not found