Fix the Calculator, Not the Tests

Make a real pytest suite pass by fixing the code under test.

A advanced Linux challenge worth 20 points. Solve it hands-on in a real Linux environment in your browser - no local setup, no fake shells.

The Challenge

Scenario: /home/labuser/lab/test_calculator.py (do not edit it) tests /home/labuser/lab/calculator.py, but add() and multiply() have the wrong operators inside them, so 2 of 5 tests currently fail.

Task: Fix the bugs in calculator.py so pytest reports all 5 tests passing. Run check when ready.