[FEAT] Add positive and negative function

[AbbeyIT]

The positive and negative function is the only button that has no function. Every time the user click it, the number should be able to change into positive or negative number.

[MiliMade]

Forked! I'd like to give this go as my first issue!

[AbbeyIT]

Awesome! Thank you @MiliMade for your interest. Issue is assigned to you now.

[AbbeyIT]

@MiliMade I updated the repo update yours to avoid confusion.

[AbbeyIT]

@MiliMade Are you still working on this issue?

[MiliMade]

Yes I am! I'm sorry I'm taking so long. Do you need it done by a certain date?

[AbbeyIT]

@MiliMade No worries. I'm just checking if you're still working on it.

[MiliMade]

Hey @AbbeyIT , I think I got it to work and created a pull request.