code: func Open(driverName, dataSourceName string) (*DB, error) {
  	db, err := sql.Open(driverName, dataSourceName)
  	if err != nil {
  		return nil, err
  	}
  	return &DB{DB: db, driverName: driverName, Mapper: mapper()}, err
  }
docs: // Open is the same as sql.Open, but returns an *sqlx.DB instead.