def clean_tos(self):
        if self.cleaned_data.get('tos', False):
            return self.cleaned_data['tos']
        raise forms.ValidationError(_(u'You must agree to the terms to register'))
Note that `ba.actor` may differ from `ar.actor` when defined on a
dataset/ETHPy150Open davemerwin/blue-channel/external_apps/registration/forms.py/RegistrationFormTermsOfService.clean_tos--crossover with--dataset/ETHPy150Open lsaffre/lino/lino/modlib/extjs/ext_renderer.py/ExtRenderer.action_call_on_instance