Push an observation onto the queue to be rendered.

def render(self, obs):
    """Push an observation onto the queue to be rendered."""
    if not self._initialized:
      return
    now = time.time()
    self._game_times.append(
        (now - self._last_time,
         max(1, obs.observation.game_loop - self._obs.observation.game_loop)))
    self._last_time = now
    self._last_game_loop = self._obs.observation.game_loop
    self._obs_queue.put(obs)
    if self._render_sync:
      self._obs_queue.join()