"Good code is its own best documentation. As you're about to add a comment, ask yourself, "How can I improve the code so that this comment isn't needed?" Improve the code and then document it to make it even clearer."

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We add that it would be all too easy to object that mutations have no evolutionary effect because they are eliminated by natural selection. Lethal mutations (the worst kind) are effectively eliminated, but others persist as alleles. ...Mutants are present within every population, from bacteria to man. There can be no doubt about it. But for the evolutionist, the essential lies elsewhere: in the fact that mutations do not coincide with evolution.

— Pierre-Paul Grasse