docs: def interior_nesting(cls, elem1, xpath, namespaces=None):
          """for elem1 containing elements at xpath, embed elem1 inside each of those elements,
          and then remove the original elem1"""
          for elem2 in elem1.xpath(xpath, namespaces=namespaces):
              child_elem1 = etree.Element(elem1.tag)
              for k in elem1.attrib:
                  child_elem1.set(k, elem1.get(k))
              child_elem1.text, elem2.text = elem2.text, ''
              for ch in elem2.getchildren():
                  child_elem1.append(ch)
              elem2.insert(0, child_elem1)
          XML.replace_with_contents(elem1)