code: def bfs(self):
      queue = deque([self])
      while queue:
          node = queue.popleft()
          yield node
          for child in node.children:
              queue.append(child)
  
imports: from abc import ABC, abstractmethod
  from collections import deque
  from typing import Any, List
  from evadb.plan_nodes.types import PlanOprType
label_desc: Use image node_id 13 for calling the AbstractPlan obj's underlying member method code with example usage: obj.bfs() without return types