func IsNotFound(err error) bool {
	return isErrCode(err, ErrCodeKeyNotFound)
}

// IsExist returns true if and only if err is "key" already exists error.
func IsExist(err error) bool {
	return isErrCode(err, ErrCodeKeyExists)
}

// IsUnreachable returns true if and only if err indicates the server could not be reached.
func IsUnreachable(err error) bool {
	return isErrCode(err, ErrCodeUnreachable)
}

}

func (e *MetricsError) Error() string {
	return e.Msg
}

// IsNotSupported returns true if and only if err is "key" not found error.
func IsNotSupported(err error) bool {
	return isErrCode(err, ErrCodeNotSupported)
}

func isErrCode(err error, code int) bool {
	if err == nil {
		return false
	}
	if e, ok := err.(*MetricsError); ok {
		return e.Code == code
	}
	return false