I want to prevent the creation of a record in the database if the first condition is met what should i return in that case.

Thanks in advance everyone

def create(self,vals):
    elv=self.env['gbv_elv'].browse(vals.get('eleveur'))
    for verif in elv.verif:
        last=verif
    if((datetime.today().date())-last.date).days < 180:
        print('hamborg')
    else:
        print('no hamborg')
        print(((datetime.today().date()) - last.date).days)
        ok=vals.get('ok')
        elv.last_date=datetime.today()
        if ok:
            elv.rate='high'
        else:
            elv.rate='low'
        return super(verifacation,self).create(vals)