关于go-redis与KeepTTL

// Set Redis `SET key value [expiration]` command.
// Use expiration for `SETEX`-like behavior.
//
// Zero expiration means the key has no expiration time.
// KeepTTL is a Redis KEEPTTL option to keep existing TTL, it requires your redis-server version >= 6.0,
// otherwise you will receive an error: (error) ERR syntax error.
func (c cmdable) Set(ctx context.Context, key string, value interface{}, expiration time.Duration) *StatusCmd {
	args := make([]interface{}, 3, 5)
	args[0] = "set"
	args[1] = key
	args[2] = value
	if expiration > 0 {
		if usePrecise(expiration) {
			args = append(args, "px", formatMs(ctx, expiration))
		} else {
			args = append(args, "ex", formatSec(ctx, expiration))
		}
	} else if expiration == KeepTTL {
		args = append(args, "keepttl")
	}

	cmd := NewStatusCmd(ctx, args...)
	_ = c(ctx, cmd)
	return cmd
}