code: func DatabasePingCheck(database *sql.DB, timeout time.Duration) Check {
  	return func() error {
  		ctx, cancel := context.WithTimeout(context.Background(), timeout)
  		defer cancel()
  		if database == nil {
  			return fmt.Errorf("database is nil")
  		}
  		return database.PingContext(ctx)
  	}
  }
docs: // DatabasePingCheck returns a Check that validates connectivity to a
  // database/sql.DB using Ping().