docs: def insertBefore(self, child: Node, ref_node: Node) -> Node:
          """Insert new child node before the reference child node.
  
          If the reference node is not a child of this node, raise ValueError. If
          this instance is connected to the node on browser, the child node is
          also added to it.
          """
          if self.connected:
              self._insert_before_web(child, ref_node)
          return self._insert_before(child, ref_node)