docs: function (node) { // returns right (remaining) subtree
              if (!node || (node.parentNode === this)) {
                  return node }
              else {
                  return this.splitSubtreeBefore (
                                      !node.previousSibling // if first node in parent, nothing to split – simply proceed to parent
                                          ? node.parentNode
                                          : document.createElement  (node.parentNode.tagName)
                                                    .copyAttributes (node.parentNode)
                                                    .insertMeBefore (node.parentNode)
                                                    .appendChildren (node.prevSiblings)
                                                    .nextSibling) } }