func (e Exception4Checker) IsValid(b m.BankAccount, sc m.SortCodeData, attempt int) bool {
	if !e.Handles(b, sc, attempt) {
		panic("Should be exception of type 4")
	}
	g := b.NumberAtPosition("g")
	h := b.NumberAtPosition("h")
	checkDigit := g*10 + h
	return GeneralChecker{}.RemainderFromRegularCheck(b, sc) == checkDigit
}
Tell if the bank account is valid
package checkers
import (
	m "github.com/AntoineAugusti/moduluschecking/models"
)
type Exception4Checker struct {
}
func (e Exception4Checker) Handles(b m.BankAccount, sc m.SortCodeData, attempt int) bool {
	return sc.IsException(4)
}