code: def get_or_create_head(root):
      
      head = _create_cssselector("head")(root)
      if not head:
          head = etree.Element("head")
          body = _create_cssselector("body")(root)[0]
          body.getparent().insert(0, head)
          return head
      else:
          return head[0]
docs: Ensures that `root` contains a <head> element and returns it.