Feature request: yas-wrap-around-region alternatively use $1 instead of $0

[rodal2]

Hello, I love yasnippet. Most of my snippets look somewhat like this:

name: square brackets

key: s

expand-env: ((yas-wrap-around-region t))

--

[$1] $0

I would love to select some text, then use yas-insert-snippet to put the selection into the square brackets and jump to $0 with TAB. I am aware that I could use the variable yas-selected-text instead but I would really like a way to either set the expansion around $1 globally or per-snippet.