First off, there’s something obviously missing from Simple: variables. In any useful language, we’d expect to be able to talk about values using meaningful names rather than the literal values themselves. These names provide a layer of indirection so that the same code can be used to process many different values, including values that come from outside the program and therefore aren’t even known when the code is written.
pay attention to the definition of variable. Here, we are not talking about storage. We can talking about naming a value. Naming a value, and then working with the name, instead of a specific value, lets us process many different values with the same code. This is the mathematical definition of a variable.
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