How to get observation space, or at least low/high bounds?

Hi,

I'm used to having observation_space in gym.Env / VectorEnv classes that tell me how to normalize observations, among other uses. Am I right to think this is missing in brax?

I'm doing
```
from brax import envs as brax_envs
vecenv = brax_envs.create("halfcheetah", batch_size=training_num)
```
and I can't find any property along the lines of observation space in the `vecenv` object