     try ParentNode.prepend(self, nodes)
   }
   public func append(nodes: Array<Either<pNode, DOMString>>) throws -> Void {
-    ParentNode.append(self, nodes)
+    try ParentNode.append(self, nodes)
   }
 
   public func query(relativeSelectors: DOMString) -> pElement? {

    try ParentNode.prepend(self, nodes)
  }
  public func append(nodes: Array<Either<pNode, DOMString>>) throws -> Void {
    ParentNode.append(self, nodes)
  }

  public func query(relativeSelectors: DOMString) -> pElement? {

    try MutationAlgorithms.preInsert(node, n, n.firstChild as? Node)
  }

  static func append(n: Node, _ nodes: Array<Either<pNode, DOMString>>) throws -> Void {
    let node = try ParentNode._convertNodesIntoNode(n, nodes)
    try MutationAlgorithms.append(node, n)
  }

  static func query(n: Node, _ relativeSelectors: DOMString) -> pElement? {return nil}
  static func queryAll(n: Node, _ relativeSelectors: DOMString) -> pElements {return Elements()}
