code: func (c *Catalog) Service(service, tag string, q *QueryOptions) ([]*CatalogService, *QueryMeta, error) {
  	var tags []string
  	if tag != "" {
  		tags = []string{tag}
  	}
  	return c.service(service, tags, q, false)
  }
docs: // Service is used to query catalog entries for a given service