you can delete the line:
Sound.GetVol
and it will still work.
You only need the {1} which will always be replaced with the payload you spoke. If you say "set volume 55", then {1} will be replaced with 55. The value will be available until the entire command has completed.
if you want to use GetVol by itself, because you didn't set the volume with a payload. Example: "what is the current volume?" Then you should use sound.getVol. But in that case the answer is not stored in {1}. You would get the answer from {lastResult}
does that make sense? Understanding this is key to being able to write and edit your own commands.