code: function traverse($node) {
    var cx = this;
    $node = _doc.ensureDoc.bind(cx)($node);
    return cx.__vnode_context == "triply" ? _traverseVNodeNext($node) : _traverseNextNode($node);
  }
docs: Traverses a document in depth-first (AKA "document") order
  In addition to every node in the document, a special `Close` node is emitted after every traversed branch.
  @param  {any} $node  (faux) VNode, Observable or any node constructed within the bound context
  @return {Observable} An Observable stream emitting VNodes