code: def feature_dim(self) -> int:
      return self._feature_dim
  
imports: import random
  from dataclasses import replace
  from typing import Any, Optional, Tuple
  import reagent.core.types
  import torch
  from reagent.core.types import CBInput
  from reagent.gym.policies.policy import Policy
  from reagent.gym.policies.samplers.discrete_sampler import GreedyActionSampler
  from reagent.gym.types import Sampler, Scorer
  from reagent.models.linear_regression import LinearRegressionUCB
  from reagent.training.cb.base_trainer import BaseCBTrainerWithEval
  from reagent.training.cb.linucb_trainer import LinUCBTrainer
  from reagent.training.parameters import LinUCBTrainerParameters
label_desc: Use image node_id 2 for calling the DynamicBanditAgent obj's underlying member method code with example usage: obj.feature_dim() and returns: self