What does it mean when a block is 'strict'?

Help with Snap! Snap! Editor
1

so Snap! v12 just released and when exploring though it, i found something like this
set [strict V] of block ({} @addInput) to []
i was wondering what it even means for a block to be ‘strict’

2

I think it might have to do with the new block type enforcements

3

Yes, that.

4

"strict" = enforce types

Also, in case people ask for that as well, here's the answer to that:
"answer" = return data type...