code: def add_link(self, link_node):
      self.__links.add(link_node)
      link_node.__links.add(self)
  
imports: import functools
  import operator
  import numpy
  import paddle
  from numpy.linalg import norm
  import cv2
label_desc: Use image node_id 4 for calling the Node obj's underlying member method code with example usage: obj.add_link(link_node) without return types