2. Variables¶
- Variables are references to memory regions that you define to use in the program. 
- The variables - Fand- Cfrom the previous example are references to memory regions.
- The variables - Fand- fare different, just as- Cand- care.
- "F"or- "C"are not variables.
2.1. Variables with defined and undefined values¶
- You can only use the content of a variable if it already has a defined value. 
- If you use a variable that has no defined value or is undefined, it would result in an error like the following. 
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