code: func (api *API) CustomHostnameIDByName(zoneID string, hostname string) (string, error) {
  	customHostnames, _, err := api.CustomHostnames(zoneID, 1, CustomHostname{Hostname: hostname})
  	if err != nil {
  		return "", errors.Wrap(err, "CustomHostnames command failed")
  	}
  	for _, ch := range customHostnames {
  		if ch.Hostname == hostname {
  			return ch.ID, nil
  		}
  	}
  	return "", errors.New("CustomHostname could not be found")
  }
docs: // CustomHostnameIDByName retrieves the ID for the given hostname in the given zone.