Possibility to add label to each flow

[mhd0528]

Hi,

I'm wondering if it's possible to add a label for each flow on the left-hand side. I went through the code and think it should be related to the 'fill between' part. May I ask if you have any suggestions on how we can change that?

Thanks.

[Pierre-Sassoulas]

I've not been working on this for a long time, you're assesment of the situation is probably better than mine if you just read the code 😄