Exercises on Section 1

Suppose that the variable till2 holds data in the form of a sequence of barcodes. When an item is read at the checkout, the state of till2 is changed by appending the barcode of the item to the end of the sequence giving the state of till2. Suppose that till2 currently has the state [50222, 50345], and that an item with barcode 50111 is read, and then an item with barcode 50456 is read. Write out the state of the variable till2 at each stage.