env.py

import gymnasium as gym
from gymnasium.vector import SyncVectorEnv

def make_env(n_envs=1, use_async_envs=False):
    def _mk():
        return gym.make("CartPole-v1")
    Vec = gym.vector.AsyncVectorEnv if use_async_envs else SyncVectorEnv
    return {"cartpole_suite": {0: Vec([_mk for _ in range(n_envs)])}}