code: def _add_physical_expr(self, expr: GroupExpression):
      self._physical_exprs.append(expr)
  
imports: from __future__ import annotations
  from typing import Dict, List
  from evadb.constants import UNDEFINED_GROUP_ID
  from evadb.optimizer.group_expression import GroupExpression
  from evadb.optimizer.property import Property
  from evadb.utils.logging_manager import logger
label_desc: Use image node_id 15 for calling the Group obj's underlying member method code with example usage: obj._add_physical_expr(expr) without return types