def METHOD_NAME(namespace):
    if namespace.user_assigned is None or len(namespace.user_assigned) == 0:
        raise InvalidArgumentValueError('Parameter "user-assigned" expected at least one argument.')
    if len(namespace.user_assigned) == 1:
        single_element = namespace.user_assigned[0].strip().lower()
        if single_element != DISABLE_LOWER and not _is_valid_user_assigned_managed_identity_resource_id(single_element):
            raise InvalidArgumentValueError('Allowed values for "user-assigned" are: {}, space-separated user-assigned managed identity resource IDs.'.format(DISABLE_LOWER))
        elif single_element == DISABLE_LOWER:
            namespace.user_assigned = [DISABLE_LOWER]
        else:
            _normalize_user_identity_resource_id(namespace)
    else:
        _validate_user_identity_resource_id(namespace)
        _normalize_user_identity_resource_id(namespace)