[Beginner's question] Set a choice as a variable

Hello,

I'm new to Ink and I'm trying to write quite a long scenario. I would like the game to remember some choices of the player. This has nothing to do with stats or such numbers - it is a pure choice.

I don't think the Ink's documentation is helpful on that subject.

So my problem looks like that.

```
=== a path
* go left
* go right

=== left
story keeps going.
* situation a (only available if gone left)
* situation b (only available if gone right)

=== right
another story keeps going
```

You get the idea. I hope.

How could I code something ? I think I need something as a marker (I began writing on InkleWriter, hence the wrong vocabulary...) but this is a language I don't speak... yet !

Thank you for your time.