code: def __str__(self) -> str:
      return "ExplainPlan()"
  
imports: from evadb.plan_nodes.abstract_plan import AbstractPlan
  from evadb.plan_nodes.types import PlanOprType
label_desc: Use image node_id 2 for calling the ExplainPlan obj's underlying member method code with example usage: obj.__str__() and returns: str