package tx import ( "errors" "fmt" ) type WrongUpdateType struct { Type string } var ( ScreenNotExistErr = errors.New("screen does not exist") SessionNotExistErr = errors.New("session does not exist") KeyboardNotExistErr = errors.New("keyboard does not exist") NotAvailableErr = errors.New("the context is not available") ) func (wut WrongUpdateType) Error() string { if wut.Type == "" { return "wrong update type" } return fmt.Sprintf("wrong update type '%s'", wut.Type) }