func (e Err) AppCode() string {
	return e.appCode
}
AppCode returns an internal code associated with the error,
so that it can be more easily recognised by clients of the API.
package errors
import (
	"fmt"
	"net/http"
)
var _ error = (*Err)(nil)
type Err struct {
	msg        string
	statusCode int
	appCode    string
}
func (e Err) Error() string {
	return e.msg
}
func (e Err) StatusCode() int {
	return e.statusCode
}