Apply sequence of actions to sequence of environments
        actions -> (observations, rewards, news)

        where 'news' is a boolean vector indicating whether each element is new.

def step(self, action):
        """
        Apply sequence of actions to sequence of environments
        actions -> (observations, rewards, news)

        where 'news' is a boolean vector indicating whether each element is new.
        """
        obs, rews, news, infos = self.env.step(action)

        self.ret = self.ret * self.gamma + rews

        obs = self._filter_observation(obs)

        if self.ret_rms:
            self.ret_rms.update(np.array([self.ret]))
            rews = np.clip(rews / np.sqrt(self.ret_rms.var + self.epsilon), -self.cliprew, self.cliprew)

        return obs, rews, news, infos