As seen here: https://bl.ocks.org/mbostock/7f5f22524bd1d824dd53c535eda0187f

function selection_clone() {
  return this.parentNode.insertBefore(this.cloneNode(true), this.nextSibling);
}

d3.selection.prototype.clone = function() {
  return this.select(selection_clone);
};

Questions:

1. Should you be allowed to do shallow clone? (Maybe?)

2. Should you be allowed to specify where to insert the cloned node, e.g., as the last child rather than immediately following the source node?