def load_env_fn(self):
    fname = os.path.join(self.logdir, 'checkpoints/env_fn.pkl')
    assert os.path.exists(fname), 'No env function saved.'
    return U.load(fname)
def load_env_fn(self):
    fname = os.path.join(self.logdir, 'checkpoints/env_fn.pkl')
    assert os.path.exists(fname), 'No env function saved.'
    return U.load(fname)