Do we need to clarify "Uni-directional data-flow"?

In the `Why?` section, when explaining the benefits of the Model Update View architecture "Uni-directional data flow" is mentioned.

> **Uni-directional data-flow** means "state" of the app is always predictable; given a specific starting "state" and sequence of update actions the output/end state will always be the same. This makes testing/testability very easy!

I am not sure, if, to somebody who just fills the prerequisites for this tutorial (basic JS knowledge, basic TDD knowledge, a computer, 30 minutes), that it is clear what uni-directional data flow is.

Do we need to clarify what it is further?
If we do think that it needs more clarification for someone of this level, is it important to have that information in this repo, or would a link to a separate explanation suffice?

Would love to get feedback from people going through this tutorial for the first time on this question!