code: func (r Dns_Domain_Registration) ModifyRegisteredNameserver(oldNameserver *string, newNameserver *string, ipAddress *string) (resp bool, err error) {
  	params := []interface{}{
  		oldNameserver,
  		newNameserver,
  		ipAddress,
  	}
  	err = r.Session.DoRequest("SoftLayer_Dns_Domain_Registration", "modifyRegisteredNameserver", params, &r.Options, &resp)
  	return
  }
docs: // The modifyRegisteredNameserver method modifies a nameserver that was registered.