vix.go
func (e *Error) Error() string {
	return fmt.Sprintf("VIX Error: %s, code: %d, operation: %s", e.Text, e.Code, e.Operation)
}
func (e *Error) Error() string {
	return fmt.Sprintf("VIX Error: %s, code: %d, operation: %s", e.Text, e.Code, e.Operation)
}
// Error returns a description of the error along with its code and operation
// implementing Go's error interface.