private function serializeNode( SerializerNode $parent, SerializerNode $node, $destroy ) {
		if ( $node->void ) {
			$contents = null;
		} else {
			$contents = '';
			foreach ( $node->children as $childIndex => $child ) {
				if ( is_string( $child ) ) {
					$contents .= $child;
				} else {
					$contents .= $this->serializeNode( $node, $child, $destroy );
				}
			}
		}
		if ( $destroy ) {
			unset( $this->nodes[$node->id] );
		}
		return $this->formatter->element( $parent, $node, $contents );
	}