pll_3.py

    def get_last_node(self) -> "Node":
        """Return the last node in the linked list"""
        current_node = self.head
        while current_node.next_node is not None:
            current_node = current_node.next_node
        return current_node

    def get_node(self, node_data: Any) -> Union["Node", None]:
        """Return the first node whose data is node_data or None"""
        current_node = self.head
        while current_node.data != node_data:
            if not current_node:
                return None
            current_node = current_node.next_node
        return current_node

    def get_prev_node(self, node_data: Any) -> Union["Node", None]:
        """Return the node before first node whose data is node_data or None"""
        current_node = self.head
        prev_node = None
        while current_node.data != node_data:
            if not current_node:
                return None
            prev_node = current_node
            current_node = current_node.next_node
        return prev_node