Try to imagine a real-world situation where the right structure to be used is a sequence. Remember that a real sequence allows elements to be repeated and assigns position to elements. Try not to get fooled by natural language use of the word “list.” A “grocery list,” for example, is not a sequence, because elements do not repeat and their position is irrelevant. Also, a student roll call may be organized in alphabetical order, but again, repetition is not allowed, and the order is again irrelevant although convenient for searching. Thus those are not real sequences.