clientv3/compare.go
func mustInt64orLeaseID(val interface{}) int64 {
	if v, ok := val.(LeaseID); ok {
		return int64(v)
	}
	return mustInt64(val)
}
func mustInt64orLeaseID(val interface{}) int64 {
	if v, ok := val.(LeaseID); ok {
		return int64(v)
	}
	return mustInt64(val)
}
// mustInt64orLeaseID panics if val isn't a LeaseID, int or int64. It returns an
// int64 otherwise.