Vereda presents simplified examples.
Programming is a constructive activity. How can a constructive, inventive activity be taught?
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What remains in our arsenal of teaching methods is the careful selection and presentation of master examples.
Niklaus Wirth
Algorithms + Data Structures = Programs
Another noteworthy characteristic of this manual is that it doesn’t always tell the truth. When certain concepts of TEX are introduced informally, general rules will be stated; afterwards you will find that the rules aren’t strictly true. In general, the later chapters contain more reliable information than the earlier ones do. The author feels that this technique of deliberate lying will actually make it easier for you to learn the ideas. Once you understand a simple but false rule, it will not be hard to supplement that rule with its exceptions.
Donald Knuth
The TEXbook