Given an Action, return the right spatial action.

def action_spatial(self, action):
    """Given an Action, return the right spatial action."""
    if self.surf.surf_type & SurfType.FEATURE:
      return action.action_feature_layer
    elif self.surf.surf_type & SurfType.RGB:
      return action.action_render
    else:
      assert self.surf.surf_type & (SurfType.RGB | SurfType.FEATURE)