def reset(self, indices=None):
    """Reset the environment and convert the resulting observation.

    Args:
      indices: The batch indices of environments to reset; defaults to all.

    Returns:
      Batch of observations.
    """
    if indices is None:
      indices = np.arange(len(self._envs))
    if self._blocking:
      observs = [self._envs[index].reset() for index in indices]
    else:
      observs = [self._envs[index].reset(blocking=False) for index in indices]
      observs = [observ() for observ in observs]
    observ = np.stack(observs)
    return observ