class_docstr: This plan is used for storing information required for union operations.
  
  Arguments:
      all: Bool
          UNION (deduplication) vs UNION ALL (non-deduplication)
code: def __hash__(self) -> int:
      return hash((super().__hash__(), self._all))
  
imports: from evadb.plan_nodes.abstract_plan import AbstractPlan
  from evadb.plan_nodes.types import PlanOprType
label_desc: Use image node_id 4 for calling the UnionPlan obj's underlying member method code with example usage: obj.__hash__() and returns: hash