docs: public static void closeAll(Closeable a, Closeable b) throws IOException {
      Throwable thrown = null;
      try {
        a.close();
      } catch (Throwable e) {
        thrown = e;
      }
      try {
        b.close();
      } catch (Throwable e) {
        if (thrown == null) thrown = e;
      }
      if (thrown == null) return;
      if (thrown instanceof IOException) throw (IOException) thrown;
      if (thrown instanceof RuntimeException) throw (RuntimeException) thrown;
      if (thrown instanceof Error) throw (Error) thrown;
      throw new AssertionError(thrown);
    }