We assume you already know how to write simple Python programs and understand basic syntax (if, for, functions, lists). Here, we're not discussing how to use the language, but why it works the way it does. If you ask a beginner what this line of code does: x = 10 the answer is usually something like: "The number 10 is stored in the variable x." At first glance, that sounds perfectly reasonable. We're used to thinking of a variable as a box or a memory cell ...