What I meant is that the lesson page has some example sentences. Now, some of them are the initial ones which are plainly visible and you can’t hide them no matter what. I wrote a crude userscript to do that, so it looks like this when it loads:
And yup, the “Lisachi” extra button handles switching between hidden/visible
I think it’s cool to be able to hide them, I’m also pretty sure it was brought up some time ago in this thread. I also chimed in with this idea. “Lisachi” button only covers the initial sentences though, as they were easy to tackle. The vanilla page for いたす looks like so:
Then, there are the study sentences on which you’re getting quizzed later on. Those have the option to be hidden:

Those are nice as they don’t spoil things for you, but…

Once you click to uncover, the button gets thanos’d into nothingness 
I think it’d be neat to have the button stay there so you can hide the TL again if you want to.
In my super-crude script it looks quite basic:

→

You can switch between visible/hidden there too. One thing I need to figure out is the extra hints, because they currently get eaten by my replacement. So it’d definitely be neat to have this out of the box.