code: def is_isolated(self):
      return len(self.edges) == 0 and len(self.r_edges) == 0
  
imports: from __future__ import annotations
  import heapq
  import itertools
  import math
  import random
  from river import base
label_desc: Use image node_id 19 for calling the Vertex obj's underlying member method code with example usage: obj.is_isolated() and returns: unknown