docs: def nextElementSibling(self) -> Optional[AbstractNode]:
          """Next Element Node.
  
          If this node has no next element node, return None.
          """
          if self.parentNode is None:
              return None
          siblings = self.parentNode.childNodes
          for i in range(siblings.index(self) + 1, len(siblings)):
              n = siblings[i]
              if n.nodeType == Node.ELEMENT_NODE:
                  return n
          return None