+=
Also written: -=
A shortcut that changes a variable using its own current value. `stock += 5` means `stock = stock + 5`, and `total += price` adds each price to a running total.
Also written: -=
A shortcut that changes a variable using its own current value. `stock += 5` means `stock = stock + 5`, and `total += price` adds each price to a running total.