code: def make(self) -> gym.Env:
      # pyre-fixme[45]: Cannot instantiate abstract class `ChangingArmsEnv`.
      return ChangingArmsEnv(self.num_arms)
  
imports: import random
  import gym
  import numpy
  import reagent.core.types
  import torch
  from reagent.core.dataclasses import dataclass
  from reagent.core.parameters import NormalizationData, NormalizationKey
  from reagent.gym.envs.env_wrapper import EnvWrapper
  from reagent.gym.normalizers import only_continuous_normalizer
label_desc: Use image node_id 1 for calling the ChangingArms obj's underlying member method code with example usage: obj.make() and returns: ChangingArmsEnv