求助 go-sql-driver/mysql调用不到Open函数

import (
    "database/sql"
    "time"

    _ "github.com/go-sql-driver/mysql"
)

// ...

db, err := sql.Open("mysql", "user:password@/dbname")
if err != nil {
    panic(err)
}
// See "Important settings" section.
db.SetConnMaxLifetime(time.Minute * 3)
db.SetMaxOpenConns(10)
db.SetMaxIdleConns(10)

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