Soft Off feature

Hi folks.

I'm looking to add the 'Soft Off' functionality to my Lily58 split board. I'm a newbie to writing firmware, so apologies if this is a simple fix.

https://deploy-preview-1942--zmk.netlify.app/docs/behaviors/soft-off

I'm following this behaviour instruction on the ZMK documentation. I add the behaviour to the top of my keymap, and then add the '&soft\_off' key binding to my layers. But then in the build, it throws an error in the WestBuild section.

It says: devicetree error: /\_\_w/zmk-config/zmk-config/config/lily58.keymap:30 (column 1): parse error: undefined node label 'soft\_off'

So it obviously doesn't like the key bindings for some reason, but I can't tell why. Any advice that anyone can give would be most appreciated.

Thanks!