code: func (m *Mercury) BatchDelete(ctx context.Context, keys []string, opts ...clientv3.OpOption) (*clientv3.TxnResponse, error) {
  	txn := m.cliv3.Txn(ctx)
  	ops := []clientv3.Op{}
  	for _, key := range keys {
  		op := clientv3.OpDelete(m.parseKey(key), opts...)
  		ops = append(ops, op)
  	}
  	return txn.Then(ops...).Commit()
  }
docs: // BatchDelete batch delete keys