Ascending vs. descending

I have quite a bit of trouble remembering what’s ascending and what’s descending. My notes:

Ascending:

• return l - r;
• if l < r: return -1; …
• oldest first
• a first, z last

Descending:

• return r - l;
• if l < r: return 1; …
• newest first
• z first, a last

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James Kerr has a way to remember. His mnemonic is “on a number line, negative numbers come first, so if l − r is negative, that means l comes first”.

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