code: func (ssa *SQLStorageAuthority) FQDNSetExists(ctx context.Context, names []string) (bool, error) {
  	exists, err := ssa.checkFQDNSetExists(
  		ssa.dbMap.WithContext(ctx).SelectOne,
  		names)
  	if err != nil {
  		return false, err
  	}
  	return exists, nil
  }
docs: // FQDNSetExists returns a bool indicating if one or more FQDN sets |names|
  // exists in the database