Add support of derevatives

guiu.rocafort.ferrer → made their first commit to this issue’s fork.

I am changing the issue status tu needs work, since i added the provided patch to the merge branch and tested it manually, but there is still need to write some tests for that functionality, which i will try to do soon.

Managed to write a test for it sooner than i expected. Setting the issue to needs review.

I am changing the issue priority as per Issue priorities → .