'Check type of a value of `radio_fields` dictionary.'

def _check_radio_fields_value(self, obj, val, label):

    from django.contrib.admin.options import HORIZONTAL, VERTICAL
    if (val not in (HORIZONTAL, VERTICAL)):
        return [checks.Error(("The    value    of    '%s'    must    be    either    admin.HORIZONTAL    or    admin.VERTICAL." % label), obj=obj.__class__, id='admin.E024')]
    else:
        return []
