public function get($active_ctx, $local_ctx) {
    $key1 = serialize($active_ctx);
    $key2 = serialize($local_ctx);
    if(property_exists($this->cache, $key1)) {
      $level1 = $this->cache->{$key1};
      if(property_exists($level1, $key2)) {
        return $level1->{$key2};
      }
    }
    return null;
  }