code: def __hash__(self):
      return hash((self.opr, tuple(self.children)))
  
file_path: evadb/evadb/optimizer/group_expression.py
imports: from typing import List
  from evadb.constants import UNDEFINED_GROUP_ID
  from evadb.optimizer.operators import Operator
  from evadb.optimizer.rules.rules_base import RuleType
label_desc: Use image node_id 14 for calling the GroupExpression obj's underlying member method code with example usage: obj.__hash__() and returns: hash