Calculator module (modules.py) implement as stack

[adamgulde]

Stacks (data structure) are perfect to implement multi-operator calculators. Currently, the calculator module, located in modules.py, uses a naive operation system. Implementing a stack would make the calculator module much more robust.

If you're taking or have taken DSA, this is a pretty straightforward problem :)

=========== Respond below (first come, first serve) if you'd like to pick up this issue

[AmariN12]

I'd like to work on this issue!

[adamgulde]

Assigned!