Add clear function

Function to remove all the items inside the stack.

What is the purpose of this function (I think I got it but maybe a bit more details would be great).

assigned to @farouq.obaly

changed the description

Allez @farouq.obaly il est temps de faire votre MR

created merge request !20 (merged) to address this issue

mentioned in merge request !20 (merged)

closed with merge request !20 (merged)

mentioned in commit 65c59a43