func NewExitError(message string, exitCode int) *ExitError {
	return &ExitError{
		exitCode: exitCode,
		message:  message,
	}
}
NewExitError makes a new *ExitError
package cli
import (
	"fmt"
	"io"
	"os"
	"strings"
)
var OsExiter = os.Exit
var ErrWriter io.Writer = os.Stderr
type MultiError struct {
	Errors []error
}
func NewMultiError(err ...error) MultiError {
	return MultiError{Errors: err}
}
func (m MultiError) Error() string {
	errs := make([]string, len(m.Errors))
	for i, err := range m.Errors {
		errs[i] = err.Error()
	}
	return strings.Join(errs, "\n")
}
type ExitCoder interface {
	error
	ExitCode() int
}
type ExitError struct {
	exitCode int
	message  string
}