`xml_replace_contents()`

[hadley]

I find I need something like this function fairly often:

xml_replace_contents <- function(node, new) {
   xml2::xml_remove(xml2::xml_contents(node))

   contents <- xml2::xml_contents(new)
   for (child in contents) {
     xml2::xml_add_child(node, child)
   }
 }

Maybe also suggests need for xml_add_children()?

[hadley]

And xml_add_child() needs a better error message when pass it a nodeset.