provider/os/os_discover.go
func (opts ListOpts) ToServerListQuery() (string, error) {
	q, err := gophercloud.BuildQueryString(opts)
	return q.String(), err
}
func (opts ListOpts) ToServerListQuery() (string, error) {
	q, err := gophercloud.BuildQueryString(opts)
	return q.String(), err
}
// ToServerListQuery formats a ListOpts into a query string.