Problems with our list data structure

• Again, our list accessing functions use a single global variable.
• What if our program required 2, or more, lists?
• Continually searching for the end-of-list can become expensive.
• Could the lists be manipulated by functions that didn't actually "understand" the data they were manipulating?

We'll address all of these by developing a similar first-in-first-out (FIFO) data structure, which we'll name a queue.