off-by-one error: n. [common] Exceedingly common error induced
in many ways, such as by starting at 0 when you should have started
at 1 or vice-versa, or by writing `< N' instead of `<= N' or
vice-versa. Also applied to giving something to the person next to
the one who should have gotten it. Often confounded with fencepost
error, which is properly a particular subtype of it.
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