retry.go
func (e Error) Error() string {
	logWithNumber := make([]string, lenWithoutNil(e))
	for i, l := range e {
		if l != nil {
			logWithNumber[i] = fmt.Sprintf("#%d: %s", i+1, l.Error())
		}
	}

	return fmt.Sprintf("All attempts fail:\n%s", strings.Join(logWithNumber, "\n"))
}
func (e Error) Error() string {
	logWithNumber := make([]string, lenWithoutNil(e))
	for i, l := range e {
		if l != nil {
			logWithNumber[i] = fmt.Sprintf("#%d: %s", i+1, l.Error())
		}
	}

	return fmt.Sprintf("All attempts fail:\n%s", strings.Join(logWithNumber, "\n"))
}
// Error method return string representation of Error
// It is an implementation of error interface