How to set zstd compression?

Help
1

I’ve tried:

encode {
    zstd 19
    gzip 9
}

and

encode {
    zstd best
    gzip best
}

but I am getting errors like:

Error: adapting config using caddyfile: parsing caddyfile tokens for ‘encode’: unexpected compression level, use one of ‘fastest’, ‘better’, ‘best’, ‘default’, at /etc/caddy/Caddyfile:5

and

Error: adapting config using caddyfile: parsing caddyfile tokens for ‘encode’: getting module named ‘http.encoders.level’: module not registered: http.encoders.level, at /etc/caddy/Caddyfile:5

the documentation under encode (Caddyfile directive) — Caddy Documentation is very not clear

2 
encode {
	zstd best
	gzip 9
}

works