def METHOD_NAME(other_key):
    def callable(key, data, errors, context):
        value = data.get(key)
        other_value = data.get(key[:-1] + (other_key,))
        if (not value or value is missing and
            not other_value or other_value is missing):
            errors[key].append(_('Missing value'))
            raise StopOnError
    return callable