code: func (p *Plugin) GetSetting(name string) string {
  	if p.Config.Settings[name] == nil {
  		pluginName := p.Config.Name
  		if len(pluginName) == 0 {
  			pluginName = "plugin"
  		}
  		m := fmt.Sprintf(
  			"missing setting %s. please declare it in the %s's plugin.json",
  			name, pluginName)
  		log.Fatal(m)
  	}
  	var val string
  	q := `SELECT value FROM settings WHERE name=$1 AND pluginname=$2`
  	err := p.DB.Get(&val, q, name, p.Config.Name)
  	if err == sql.ErrNoRows {
  		return p.Config.Settings[name].Default
  	}
  	if err != nil {
  		log.Info("failed to get plugin setting.", err)
  		return ""
  	}
  	return val
  }
docs: // GetSetting retrieves a specific setting's value. It throws a fatal error if
  // the setting has not been declared in the plugin's plugin.json file.