code: def __str__(self) -> str:
      return "AbstractPlan"
  
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 10 for calling the AbstractPlan obj's underlying member method code with example usage: obj.__str__() and returns: str