You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: slackconf.go
    path of file: ./repos/vuls/config
    
    the code of the file until where you have to start completion: package config

import (
	"strings"

	"github.com/asaskevich/govalidator"
	"golang.org/x/xerrors"
)

// SlackConf is slack config
type SlackConf struct {
	HookURL     string   `valid:"url" json:"-" toml:"hookURL,omitempty"`
	LegacyToken string   `json:"-" toml:"legacyToken,omitempty"`
	Channel     string   `json:"-" toml:"channel,omitempty"`
	IconEmoji   string   `json:"-" toml:"iconEmoji,omitempty"`
	AuthUser    string   `json:"-" toml:"authUser,omitempty"`
	NotifyUsers []string `toml:"notifyUsers,omitempty" json:"-"`
	Text        string   `json:"-"`
	Enabled     bool     `toml:"-" json:"-"`
}

// Validate va
    
func (c *SlackConf) Validate() (errs []error) {
	if !c.Enabled {
		return
	}

	if len(c.HookURL) == 0 && len(c.LegacyToken) == 0 {
		errs = append(errs, xerrors.New("slack.hookURL or slack.LegacyToken must not be empty"))
	}

	if len(c.Channel) == 0 {
		errs = append(errs, xerrors.New("slack.channel must not be empty"))
	} else {
		if !(strings.HasPrefix(c.Channel, "#") ||
			c.Channel == "${servername}") {
			errs = append(errs, xerrors.Errorf(
				"channel's prefix must be '#', channel: %s", c.Channel))
		}
	}

	if len(c.AuthUser) == 0 {
		errs = append(errs, xerrors.New("slack.authUser must not be empty"))
	}

	_, err := govalidator.ValidateStruct(c)
	if err != nil {
		errs = append(errs, err)
	}

	return
}