code: def __init__(
      self,
      opr: Operator,
      group_id: int = UNDEFINED_GROUP_ID,
      children: List[int] = [],
  ):
      # remove this assert after fixing
      # optimizer_context:_xform_opr_to_group_expr
      assert (
          len(opr.children) == 0
      ), """Cannot create a group expression
                                  from operator with children"""
      self._opr = opr
      self._group_id = group_id
      self._children = children
      self._rules_explored = RuleType.INVALID_RULE
  
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 1 to create a new GroupExpression object  with example: obj = GroupExpression(opr, group_id, children)