code: def get_column_nodes(self) -> List[Union[Column, "Feature"]]:
      res = []
      for child in self.children:
          res.extend(child.get_column_nodes())
      return res
  
imports: import hashlib
  import itertools
  from typing import Dict, List, Optional, Tuple, Union
  import numpy
  import pandas
  from pandas._typing import DtypeObj
  from upgini.autofe.all_operands import find_op
  from upgini.autofe.operand import Operand, PandasOperand
label_desc: Use image node_id 6 for calling the Feature obj's underlying member method code with example usage: obj.get_column_nodes() and returns: res