isOdd should not need to be a function
Hence "trivial examples are a bad basis for maintainability discussions". In the provided code there is no "elsewhere" so it really doesn't need to be a function at that time (YAGNI and all that, and Donald Knuth had strong opinions on this one too).
Anyway, in a language with a less poor standard library we wouldn't have to define simple functions to check an integer's parity, so I think this discussion has run its course.
Ruby has it as a function 😉
Ruby has it as a method. ;-) And I think what Sean meant is exactly that: common functionality like this should be part of the core language, so people don't have to go and implement it themselves every time.
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