code: func (tx *Tx) CopyTo(w io.Writer, query interface{}, params ...interface{}) (res Result, err error) {
  	err = tx.withConn(context.TODO(), func(cn *pool.Conn) error {
  		res, err = tx.db.copyTo(cn, w, query, params...)
  		return err
  	})
  	return res, err
  }
docs: // CopyTo is an alias for DB.CopyTo.